bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscibility of Polythiophene‐graft‐poly(methyl methacrylate) brushes with Poly(vinylidene fluoride): Morphology, Optical and Conductivity Properties
Authors: Mandal Amit , Nandi Arun K. 
Published: June 2011

AbstractPolythiophene‐graft‐poly(methyl methacrylate) brushes are synthesized by ATRP. They form miscible blends with poly(vinylidene fluoride) (PVDF) due to specific interactions between the >CO groups of PT‐g‐PMMA with the >CF2 groups of PVDF. PT‐g‐PMMA remains in the interlamellar, interfibrillar and interspherulitic regions of the PVDF crystals at both laterally and longitudinally aggregated states. In the blends both PVDF and PT‐g‐PMMA brushes have nanometer sizes, producing nanostructured polymer blends. The PL intensity can be tuned by varying the PT‐g‐PMMA concentration, and the blend exhibits good dc conductivity with a percolation threshold at 10 wt.‐% PT‐g‐PMMA. Conductivity data indicate a conformational transition of PT‐g‐PMMA chains with increasing temperature. magnified image
Synthesis of Water‐Soluble Copolymers Carrying Long‐Chain (C12 to C30) Aliphatic Moieties
Authors: Barroso‐Bujans Fabienne , Yazdani‐Pedram Mehrdad , Frey Holger , Martínez Ricardo 
Published: June 2011

AbstractWater‐soluble copolymers from mono‐1‐alkyl itaconates and N‐vinyl‐2‐pyrrolidone are synthesized and characterized. The mono‐1‐alkyl itaconates are prepared from itaconic anhydride and the related alcohol: 1‐dodecanol, 1‐octadecanol, 1‐docosanol, and 1‐triacontanol. The mono‐1‐triacontyl itaconate is synthesized from plant growth regulator policosanols extracted from Agave fourcrouydes, where 1‐triacontanol is the major product. The reactivity ratios, calculated according to the Mao‐Huglin method for copolymerizations conducted to medium‐high conversions, indicate a tendency toward alternation for all copolymerization reactions. Water solubility of copolymers is provided as a function of copolymer composition and aliphatic chain length. magnified image
Pollen: A Novel, Biorenewable Filler for Polymer Composites
Authors: Lee Jung‐Hyun , Suttle Brandon M. , Kim Hyung‐Ju , Meredith J. Carson 
Published: June 2011

AbstractPollen has an exine shell with remarkable chemical stability, high‐strength, and unique microstructures that suggest use as a biorenewable polymer filler. Pollen‐filled polymers may offer potential for light‐weight, high‐strength materials that can displace some petroleum‐derived content with a sustainable plant‐based alternative. We report the first demonstration of the incorporation of pollen grains (short ragweed) on the mechanical, interfacial, and thermal properties of two polymers, poly(ε‐caprolactone) (PCL) and polystyrene (PS). Under certain solvent and annealing conditions, PS mechanical properties were improved synergistically upon addition of pollen, while those of PCL were always degraded, in strong agreement with wetting behavior of the polymer–pollen interface. magnified image
The Effect of Mixing on the Mechanical Properties of Hyaluronan‐Based Injectable Hydrogels
Authors: Piskounova Sonya , Rojas Ramiro , Bergman Kristoffer , Hilborn Jöns 
Published: June 2011

AbstractA method for determining the correlation between the mixing of two reactive polymers and the structural and mechanical properties of the formed hydrogels is presented. Rheological measurements show that insufficient mixing gives rise to soft and not fully crosslinked hydrogels while excessive mixing beyond gel point results in weaker hydrogels due to potential breakage of their 3D network. Furthermore, the hydrogels swell significantly more in cell culture medium than in phosphate‐buffered saline, attributed to interactions with additional molecules such as proteins. Thus, moderate mixing gives rise to the most homogenous and mechanically stable hydrogels and the choice of medium e.g., for release experiments, should be consistent in order to avoid unnecessary variations in the data caused by different swelling profiles. magnified image
Functionalized Graphene–PVDF Foam Composites for EMI Shielding
Authors: Eswaraiah Varrla , Sankaranarayanan Venkataraman , Ramaprabhu Sundara 
Published: June 2011

AbstractNovel foam composites comprising functionalized graphene (f‐G) and polyvinylidene fluoride (PVDF) were prepared and electrical conductivity and electromagnetic interference (EMI) shielding efficiency of the composites with different mass fractions of f‐G have been investigated. The electrical conductivity increases with the increase in concentration of f‐G in insulating PVDF matrix. A dramatic change in the conductivity is observed from 10−16 S · m−1 for insulating PVDF to 10−4 S · m−1 for 0.5 wt.% f‐G reinforced PVDF composite, which can be attributed to high‐aspect‐ratio and highly conducting nature of f‐G nanofiller, which forms a conductive network in the polymer. An EMI shielding effectiveness of ≈20 dB is obtained in X‐band (8–12 GHz) region and 18 dB in broadband (1–8 GHz) region for 5 wt.% of f‐G in foam composite. The application of conductive graphene foam composites as lightweight EMI shielding materials for X‐band and broadband shielding has been demonstrated and the mechanism of EMI shielding in f‐G/PVDF foam composites has been discussed. magnified image
Synthesis and Polymerization of Renewable 1,3‐Cyclohexadiene Using Metathesis, Isomerization, and Cascade Reactions with Late‐metal Catalysts
Authors: Mathers Robert T. , Shreve Michael J. , Meyler Etan , Damodaran Krishnan , Iwig David F. , Kelley Diana J. 
Published: June 2011

AbstractSynthesis and subsequent polymerization of renewable 1,3‐cyclohexadiene (1,3‐CHD) from plant oils is reported via metathesis and isomerization reactions. The metathesis reaction required no plant oil purification, minimal catalyst loading, no organic solvents, and simple product recovery by distillation. After treating soybean oil with a ruthenium metathesis catalyst, the resulting 1,4‐cyclohexadiene (1,4‐CHD) was isomerized with RuHCl(CO)(PPh3)3. The isomerization reaction was conducted for 1 h in neat 1,4‐CHD with [1,4–CHD]/[RuHCl(CO)(PPh3)3] ratios as high as 5 000. The isomerization and subsequent polymerization of the renewable 1,3‐CHD was examined as a two‐step sequence and as a one‐step cascade reaction. The polymerization was catalyzed with nickel(II)acetylacetonate/methaluminoxane in neat monomer, hydrogenated d‐limonene, and toluene. The resulting polymers were characterized by FTIR, DSC, and TGA. magnified image
Temperature‐ and Redox‐Directed Multiple Self Assembly of Poly(N‐Isopropylacrylamide) Grafted Dextran Nanogels
Authors: Lv Weipeng , Liu Shuoqi , Feng Wenqian , Qi Junjie , Zhang Guoliang , Zhang Fengbao , Fan Xiaobin 
Published: June 2011

AbstractPoly(N‐isopropylacrylamide) (PNIPAAm) grafted dextran nanogels with dodecyl and thiol end groups have been synthesized by RAFT process. Dodecyl‐terminated polymers (DexPNI) can be readily dissolved in water and further self assemble into ordered stable nanostructures through direct noncovalent interactions at room temperature. SEM, AFM and DLS measurements confirm the formation of spherical nanogels at hundred‐nanometer scales. The elevation of environment temperature will indirectly result in the formation of collapsed nanostructures due to the LCST phase transition of PNIPAAm side chains. Turbidimetry results show that the phase transition behaviors of DexPNI are greatly dependent on PNIPAAm chain length and polymer concentration: increasing PNIPAAm chain length and polymer concentration both lead to lower LCSTs and sharper phase transitions. Moreover, the dodecyl‐terminated polymers can transform into thiol‐terminated versions by aminolysis of trithiocarbonate groups, and further into chemical (disulfide) cross‐linked versions (SS‐DexPNI) by oxidation. SS‐DexPNI nanogels have “doubled” chain length of PNIPAAm, and hence sharper phase transitions. In situ DLS measurements of the evolution of hydrodynamic radius attest that the self assembly of SS‐DexPNI nanogels can be selectively directed by the change in either external temperature or redox potential. These nanogels thus are promising candidates for triggered intracellular delivery of encapsulated cargo. We can also expect that the polymer can be noncovalently (by dodecyl end groups) or covalently (by thiol end groups) coated on a series of nanomaterials (e.g., carbon nanotubes, graphene, gold nanomaterials) to build a variety of novel smart, and robust nanomaterials. magnified image
Design of Bimodal PCL and PCL‐HA Nanocomposite Scaffolds by Two Step Depressurization During Solid‐state Supercritical CO2 Foaming
Authors: Salerno Aurelio , Zeppetelli Stefania , Di Maio Ernesto , Iannace Salvatore , Netti Paolo Antonio 
Published: June 2011

AbstractThis communication reports the design and fabrication of porous scaffolds of poly(ε‐caprolactone) (PCL) and PCL loaded with hydroxyapatite (HA) nanoparticles with bimodal pore size distributions by a two step depressurization solid‐state supercritical CO2 (scCO2) foaming process. Results show that the pore structure features of the scaffolds are strongly affected by the thermal history of the starting polymeric materials and by the depressurization profile. In particular, PCL and PCL‐HA nanocomposite scaffolds with bimodal and uniform pore size distributions are fabricated by quenching molten samples in liquid N2, solubilizing the scCO2 at 37 °C and 20 MPa, and further releasing the blowing agent in two steps: (1) from 20 to 10 MPa at a slow depressurization rate, and (2) from 10 MPa to the ambient pressure at a fast depressurization rate. The biocompatibility of the bimodal scaffolds is finally evaluated by the in vitro culture of human mesenchymal stem cells (MSCs), in order to assess their potential for tissue engineering applications. magnified image
Low Temperature Aqueous Living/Controlled (RAFT) Polymerization of Carboxybetaine Methacrylamide up to High Molecular Weights
Authors: Rodriguez‐Emmenegger Cesar , Schmidt Bernhard V. K. J. , Sedlakova Zdenka , Šubr Vladimir , Alles Aldo Bologna , Brynda Eduard , Barner‐Kowollik Christopher 
Published: June 2011

AbstractAmong the class of zwitterionic polymers poly(carboxybetaine)s (poly(CB)s) are unique, emerging as the only ultra‐low fouling materials known allowing the preparation of biosensors, fouling resistant nanoparticles, and non‐adhesive surfaces for bacteria. Poly(carboxybetaine methacrylate) and poly(carboxybetaine acrylamide) have been prepared via atom transfer radical polymerization (ATRP), however a polymerization with living characteristics has not been achieved yet. Herein, the first successful living/controlled reversible addition fragmentation transfer (RAFT) polymerization of (3‐methacryloylamino‐propyl)‐(2‐carboxy‐ethyl)‐dimethyl‐ammonium (carboxybetaine methacrylamide) (CBMAA‐3) in acetate buffer (pH 5.2) at 70 and 37 °C is reported. The polymerization afforded very high molecular weight polymers (determined by absolute size exclusion chromatography, close to 250 000 g · mol−1 in less than 6 h) with low PDI (<1.3) at 70 °C. The polymerization was additionally carried out at 37 °C allowing to achieve yet lower PDIs (1.06 ≤ PDI ≤ 1.15) even at 90% conversion, demonstrating the suitability of the polymerization conditions for bioconjugate grafting. The living character of the polymerization is additionally evidenced by chain extending poly(CBMAA‐3) at 70 and 37 °C. Block copolymerization from biologically relevant poly[N‐(2‐hydroxypropyl)methacrylamide] macroCTAs was additionally performed. magnified image
Frontal Polymerization: Polymerization Induced Destabilization of Peracrylates
Authors: Gugg Astrid , Gorsche Christian , Moszner Norbert , Liska Robert 
Published: June 2011

AbstractFrontal photopolymerization has attracted much attention in the last decade as it allows the curing of thick films. Unfortunately, the use of peroxides, which feature appropriate storage stability, also requires inappropriately high initiation temperatures. Here, a new approach involving a copolymerisation‐induced destabilization of (meth)acrylate‐based peroxides that allows lower front temperatures is presented. The increasing degree of branching next to the carbonyl group lowers the decomposition temperature by at least 20 °C. In classical monomer formulations, sufficient storage stability is confirmed. magnified image
Polymer Brushes Showing Non‐Fouling in Blood Plasma Challenge the Currently Accepted Design of Protein Resistant Surfaces
Authors: Rodriguez‐Emmenegger Cesar , Brynda Eduard , Riedel Tomas , Houska Milan , Šubr Vladimir , Alles Aldo Bologna , Hasan Erol , Gautrot Julien E. , Huck Wilhelm T. S. 
Published: June 2011

AbstractUltra‐low‐fouling poly[N‐(2‐hydroxypropyl) methacrylamide] (poly(HPMA)) brushes have been synthesized for the first time. Similar to the so far only ultra‐low‐fouling surface, poly(carboxybetaine acrylamide), the level of blood plasma fouling was below the detection limit of surface plasmon resonance (SPR, 0.03 ng · cm−2) despite being a hydrogen bond donor and displaying a moderate wettability, thus challenging the currently accepted views for the design of antifouling properties. The antifouling properties were preserved even after two years of storage. To demonstrate the potential of poly(HPMA) brushes for the preparation of bioactive ultra‐low fouling surfaces a label‐free SPR immunosensor for detection of G Streptococcus was prepared. magnified image
Controllable Optical, Electrical, and Morphologic Properties of 3,4‐Ethylenedioxythiophene Based Electrocopolymerization Films
Authors: Gu Cheng , Liu He , Hu Dehua , Zhang Wensi , Lv Ying , Lu Ping , Lu Dan , Ma Yuguang 
Published: June 2011

AbstractThis contribution presents a kind of novel and neutral network films based on EDOT formed by in situ electrocopolymerization (ECP). The ECP films which are neutral and colorless exhibit the conductivity of 0.2–0.5 S · cm−1, WF of 4.79–5.20 eV, and RMS roughness of 3.51–5.26 nm. The electroluminescent devices where ECP films acted as hole‐transport layer (HTL) exhibit higher brightness, current density, efficiency (20–30% improvement), and stability than that of PEDOT:PSS HTL device. The ECP films also significantly benefit the stability of neighboring organic layer compared to PEDOT:PSS. This kind of new ECP films affords more opportunities to develop organic light‐emitting diodes (OLEDs) with high performances and stability. magnified image
Modeling Anisotropic Elasticity of Fluid Membranes
Authors: Ramakrishnan N. , Kumar P. B. Sunil , Ipsen John H. 
Published: June 2011

AbstractThe biological membrane, which compartmentalizes the cell and its organelles, exhibits wide variety of macroscopic shapes of varying morphology and topology. A systematic understanding of the relation of membrane shapes to composition, external field, environmental conditions, etc. have important biological relevance. Here we review the triangulated surface model, used in the macroscopic simulation of membranes and the associated DTMC methods. New techniques to calculate surface quantifiers, that will facilitate the study of additional in‐plane orientational degrees of freedom, has been introduced. The mere presence of a polar and nematic fields, in the ordered phase, drives the ground state conformations of the membrane to a cylinder and tetrahedron, respectively. magnified image
Full Molecular Weight Distribution in RAFT Polymerization. New Mechanistic Insight by Direct Integration of the Equations
Authors: Zapata‐González Iván , Saldívar‐Guerra Enrique , Ortiz‐Cisneros José 
Published: June 2011

AbstractThe full molecular weight distribution (FMWD) equations in RAFT polymerization are solved by direct integration for three models: intermediate radical termination (IRT), slow fragmentation (SF), and IRT with oligomers (IRTO). It is shown that the quasi steady state approximation (QSSA) is always applicable to living radicals, and also applicable to intermediate radicals in the IRT and IRTO models. The application of the QSSA allows for considerable simplification of the numerical solution of the equations. A marked bimodality is found for the FMWD of the SF model only. This suggests model discrimination by radical trapping experiments followed by GPC measurement of the total MWD. magnified image
Effect of N‐(p‐coumaroyl)serotonin and N‐feruloylserotonin, major anti‐atherogenic polyphenols in safflower seed, on vasodilation, proliferation and migration of vascular smooth muscle cells
Authors: Takimoto Tetsuya , Suzuki Katsuya , Arisaka Harumi , Murata Takahisa , Ozaki Hiroshi , Koyama Naoto 
Published: June 2011

AbstractScope: The objective of this study is to investigate a vascular effect of N‐(p‐coumaroyl)serotonin (CS) and N‐feruloylserotonin (FS), major antioxidative indolic polyphenols in safflower seeds with anti‐atherogenic properties, with emphasis on effects on vascular smooth muscle cells (VSMCs).Methods and results: Both CS and FS (each 10 to 100 μM) relaxed rat femoral arteries, which were pre‐contracted by 10−5 M phenylephrine or 50 mM KCl, independently of their endothelium. Both CS and FS also concentration‐dependently inhibited the increase of cytosolic free Ca2+ concentration ([Ca2+]i) that was induced by KCl or 5‐hydroxytryptamine in cultured rat VSMCs. Next, we examined the effects of CS and FS on platelet‐derived growth factor (PDGF)‐BB‐evoked proliferation and migration of the VSMCs. Both CS and FS inhibited PDGF‐BB‐evoked proliferation and migration of the VSMCs in a concentration‐dependent manner. They also inhibited PDGF‐BB‐induced phosphorylation of PDGF receptor β and ERK1/2, and Ca2+ release from sarcoplasmic reticulum in the VSMCs in a concentration‐dependent fashion.Conclusion: These results indicated a possible vascular effect of CS/FS to inhibit the activation of VSMCs by blocking the increase of [Ca2+]i and/or blocking PDGF signaling. These may explain a part of anti‐atherogenic mechanism that underlies their ability to improve vascular distensibility and to inhibit aortic hyperplasia.
Role of membrane dynamics processes and exogenous molecules in cellular resveratrol uptake: Consequences in bioavailability and activities
Authors: Delmas Dominique , Lin Hung‐Yun 
Published: June 2011

AbstractIn the fields of nutrition prevention and therapy treatment, numerous studies have reported interesting properties of trans‐resveratrol (RSV), a natural polyphenol against pathologies such as vascular diseases, cancers, viral infections and neurodegenerative processes. These beneficial effects are supported by more studies showing the pleiotropic actions of RSV. Nevertheless, a crucial question concerning these effects is how the polyphenol, when applied to an organism, gains access to its targets. In this review, we focus on the biochemical and biological parameters involved in RSV transport, particularly the role of the phospholipid bilayer in RSV uptake (passive diffusion, carrier‐mediated transport) and of exogenous molecules modulating RSV transport and effects. The dynamic processes of the plasma membrane reveal the importance of the role of lipid composition in the fluidity, the lipid rafts in RSV endocytosis and the ATP‐binding cassette transporters in RSV efflux. Specific membrane receptors such as integrin αvβ3 contribute to RSV uptake and to activate signalling pathways involved in apoptosis. We discuss the role of intracellular receptors (i.e. aryl‐hydrocarbon and estrogen receptors). In addition, circulating molecules (i.e. albumin, haemoglobin, fatty acids, lipoproteins) play a role as RSV carriers. Finally, we developed a hypothesis concerning the relation between RSV uptake and its biological activities.
Extrusion cooking with glucose supplementation of fumonisin‐contaminated corn grits protects against nephrotoxicity and disrupted sphingolipid metabolism in rats
Authors: Voss Kenneth A. , Riley Ronald T. , Jackson Lauren S. , Jablonski Joseph E. , Bianchini Andreia , Bullerman Lloyd B. , Hanna Milford A. , Ryu Dojin 
Published: June 2011

AbstractScope: Fumonisin B1 (FB1) is a mycotoxin found in maize and maize‐based foods. It causes animal diseases and is a suspected risk factor for cancer and birth defects in humans. Extrusion cooking reduces FB1 concentrations in maize however toxicity caused by unknown degradation or FB1‐matrix reaction products might persist.Methods and results: To test the efficacy of extrusion to reduce FB1 toxicity, Fusarium verticillioides fermented corn (= maize) grits (Batch‐1= 9.7 ppm FB1; Batch‐2= 50 ppm FB1) were extruded without (Batch‐1E; Batch‐2E) or with 10% glucose supplementation (Batch‐1EG; Batch‐2EG). FB1 concentrations were reduced 64% (Batch‐2E) to 94% (Batch‐1EG) after cooking. When the uncooked and processed grits were fed (50% w/w in rodent chow) to rats for up to 8 weeks, FB1 intakes averaged 354, 103, and 25.1 çg/kg body weight/day for Batch‐1, Batch‐1E and Batch‐1EG and 1804, 698, and 222 çg/kg body weight/day for the Batch‐2, Batch‐2E and Batch‐2EG, respectively. Nephrotoxicity including apoptotic lesions and elevated sphingoid base concentrations decreased in a dose‐dependent manner in groups fed Batch‐1, Batch‐1E, Batch‐2, Batch‐2E, or Batch‐2EG and was absent in the Batch‐1EG group.Conclusion: Extrusion cooking, especially with glucose supplementation, is potentially useful to reduce FB1 concentrations and toxicity of FB1‐contaminated maize.
The inhibitory effects of 5‐hydroxy‐3,6,7,8,3′,4′‐hexamethoxyflavone on human colon cancer cells
Authors: Qiu Peiju , Guan Huashi , Dong Ping , Guo Shanshan , Zheng Jinkai , Li Shiming , Chen Yun , Ho Chi‐Tang , Pan Min‐Hsiung , McClements David Julian , Xiao Hang 
Published: June 2011

AbstractScope: Previously, we reported that 5‐hydroxy‐3,6,7,8,3′,4′‐hexamethoxyflavone (5HHMF), a polymethoxyflavone found in citrus peels, potently inhibited the growth of multiple human colon cancer cells. Herein, we further investigated the anti‐cancer mechanisms of 5HHMF in human colon cancer cells.Methods and results: Colony formation assay revealed that 5HHMF dose dependently inhibited colony formation of multiple colon cancer cells. Western blot analysis demonstrated 5HHMF decreased nuclear β‐catenin levels and increased the E‐cadherin level in a dose‐dependent manner. 5HHMF also modified plasma membrane‐associated proteins, such as K‐Ras, EGFR, and their downstream effectors, such as Akt. Moreover, treatments with 5HHMF inhibited nuclear translocation of NF‐κB, which may contribute to its anti‐cancer effects. Add‐back study showed that the inhibitory effect of 5HHMF was not associated with the production of reactive oxygen species (ROS). In addition, 5HHMF treatment inhibited the capillary tube formation of human umbilical vein endothelial cells (HUVECs) on matrigel, suggesting a potential anti‐tumor angiogenesis effect.Conclusion: Our results demonstrated that 5HHMF suppressed multiple oncogenic molecular events in colon cancer cells.
Unscented Transformation‐Based Filters: Performance Comparison Analysis for the State Estimation in Polymerization Processes with Delayed Measurements
Authors: Galdeano Rubén , Asteasuain Mariano , Sánchez Mabel 
Published: June 2011

AbstractState estimation with delayed measurements is essential to the operation of polymer processes due to the limited availability of reliable online sensors and the unavoidable hold‐up time in the acquisition of critical variables data. In this work, a two‐timescale approach is applied to three filters based on the Unscented Transformation, the Unscented Kalman Filter, the Unscented Recursive Nonlinear Dynamic Data Reconciliation and the Reformulated Constrained Unscented Kalman Filter, in order to incorporate delayed measurements into their estimation scheme. A comprehensive comparative analysis is performed, which shows that the three of them have very good accuracy and convergence properties. However, the Unscented Kalman Filter performs better in terms of computational time. magnified image