Thu, 21 Aug 2008 00:01:43 BST CiteULike: Tag polymers http://www.citeulike.org/tag/polymers CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/tilana/article/304602 <i>Polymer, Vol. 46, No. 19. (8 September 2005), pp. 7803-7818.</i><br /><br />The behavior of mixtures of polymers with carbon nanotubes are reviewed. The use of polymers as dispersing agents of individual CNT is described in detail. Two groups of polymer-CNT systems are presented. One corresponds to the case in which the polymer-CNT interactions modify the electronic properties of the tubes. The second case corresponds to the polymers end-tethered to the tubes. This case results in changing the inter-tube interactions from strongly attractive to repulsive, through the entropic (steric) polymer induced repulsions. It is shown that the shape and dimensionality of the tubes determines the strength, range and type of inter-tube van der Waals attractions and polymer induced repulsions. The experimental verification of these ideas, and their implications for tube dispersions and separation are discussed. Polymers and carbon nanotubes--dimensionality, interactions and nanotechnology Igal Szleifer Rachel Yerushalmi-Rozen doi:10.1016/j.polymer.2005.05.104 Polymer, Vol. 46, No. 19. (8 September 2005), pp. 7803-7818. 2005-08-26T14:02:16-00:00 2005 Polymer 46 19 7803 7818 and carbon nanotubes polymers http://www.citeulike.org/user/softsimu/article/2790025 <i>Polymer, Vol. 45, No. 17. (5 August 2004), pp. 5995-6002.</i><br /><br />Persistence length of (bio)macromolecules plays an increasingly important role in macromolecular science, especially in emerging fields like macromolecular biophysics. It is shown that using established approximate relations for the estimation of persistence length for semi-flexible macromolecules leads to differences between different methods or even to a modified behavior, especially at high chain stiffness. The approximate estimate obtained from the average bond angle (B) performs better than the estimate from the decay of bond orientation correlation (C) in chain but close to the coil-to-rod transition starts to fail. This approximate estimate is close to the estimate from the definition of persistence (D) (with minimum approximations) not only in the theta state or the random coil but also in the good solvent. The value of persistence from the decay of bond orientation correlation along the macromolecule is underestimated when compared to the exact value. The persistence obtained from the worm-like chain model (W) is close to the exact result in the coil regime (also in the good solvent) but near at and above the transition produces the largest values of all approximations. In systems with interactions this model starts to underestimate the persistence on decreasing temperature. We advocate using the estimate (D) of persistence length generally since it avoids limitations mentioned above and at the same time does not pose additional requirements on the evaluation itself. Differences and limits in estimates of persistence length for semi-flexible macromolecules P Cifra doi:10.1016/j.polymer.2004.06.034 Polymer, Vol. 45, No. 17. (5 August 2004), pp. 5995-6002. 2008-05-12T16:46:36-00:00 2004 Polymer 45 17 5995 6002 length persistence polymers http://www.citeulike.org/user/softsimu/article/2415530 <i>The Journal of Chemical Physics, Vol. 114, No. 17. (2001), pp. 7644-7654.</i><br /><br />  Phase behavior of monomeric mixtures and polymer solutions with soft interaction potentials CM Wijmans B Smit RD Groot doi:10.1063/1.1362298 The Journal of Chemical Physics, Vol. 114, No. 17. (2001), pp. 7644-7654. 2008-02-22T19:35:08-00:00 2001 The Journal of Chemical Physics 114 17 7644 7654 AIP coarse-graining dpd polymers http://www.citeulike.org/user/softsimu/article/2805784 <i>EPL (Europhysics Letters), Vol. 45, No. 4. (1999), pp. 488-494.</i><br /><br />The influence of molecular stiffness on the dynamic properties of polymer melts is investigated analytically. It is shown that the relaxation times characterizing the internal dynamics of the polymer chains exhibit a crossover from Rouse to bending modes with increasing mode number. As a consequence the mean square displacement of monomers and the dynamic structure factor are strongly influenced by the molecular stiffness. The comparison of both equilibrium and dynamical properties of n-alkane chains in a melt with recent molecular dynamics simulations and neutron scattering experiments exhibits excellent agreement. On the dynamics of polymer melts: Contribution of Rouse and bending modes L Harnau RG Winkler P Reineker doi:10.1209/epl/i1999-00193-6 EPL (Europhysics Letters), Vol. 45, No. 4. (1999), pp. 488-494. 2008-05-16T19:55:19-00:00 1999 EPL (Europhysics Letters) 45 4 488 494 factor polymers structure http://www.citeulike.org/user/softsimu/article/2096024 <i>Nat Mater, Vol. 2, No. 11. (November 2003), pp. 762-766.</i> Nanoscale effects leading to non-Einstein-like decrease in viscosity Michael Mackay Tien Dao Anish Tuteja Derek Ho Brooke Van Horn Ho-Cheol Kim Craig Hawker doi:10.1038/nmat999 Nat Mater, Vol. 2, No. 11. (November 2003), pp. 762-766. 2007-12-12T00:02:22-00:00 2003 Nat Mater 2 11 762 766 Nature Publishing Group polymers viscosity http://www.citeulike.org/user/softsimu/article/2096023 <i>Nat Mater, Vol. 6, No. 12. (December 2007), pp. 961-965.</i> Enhanced mobility of confined polymers Kyusoon Shin Sergei Obukhov Jiun-Tai Chen June Huh Yoontae Hwang Soonchun Mok Priyanka Dobriyal Pappannan Thiyagarajan Thomas Russell doi:10.1038/nmat2031 Nat Mater, Vol. 6, No. 12. (December 2007), pp. 961-965. 2007-12-12T00:00:58-00:00 2007 Nat Mater 6 12 961 965 Nature Publishing Group polymers http://www.citeulike.org/user/softsimu/article/2098939 <i>Phys. Rev. E Stat. Nonlinear Soft Matter Phys., Vol. 75, No. 3. (2007), 036713.</i><br /><br />Understanding the fundamental properties of polymeric liquids remains a challenge in materials science and soft matter physics. Here, we present a simple and computationally efficient criterion for topological constraints, i.e., uncrossability of chains, in polymeric liquids using the dissipative particle dynamics (DPD) method. No new length scales or forces are added. To demonstrate that this approach really prevents chain crossings, we study a melt of linear homopolymers. We show that for short chains the model correctly reproduces Rouse-like dynamics whereas for longer chains the dynamics becomes reptational as the chain length is increaseda??"something that is not attainable using standard DPD or other coarse-grained soft potential methods. © 2007 The American Physical Society. Art. No.: 036713 Reptational dynamics in dissipative particle dynamics simulations of polymer melts P Nikunen I Vattulainen M Karttunen doi:10.1103/PhysRevE.75.036713 Phys. Rev. E Stat. Nonlinear Soft Matter Phys., Vol. 75, No. 3. (2007), 036713. 2007-12-12T14:19:02-00:00 2007 Phys. Rev. E Stat. Nonlinear Soft Matter Phys. 75 3 036713 dpd polymers reptation rouse http://www.citeulike.org/user/softsimu/article/2277834 <i>Reviews of Modern Physics, Vol. 64, No. 3. (July 1992), 645.</i> Soft matter PG de Gennes doi:10.1103/RevModPhys.64.645 Reviews of Modern Physics, Vol. 64, No. 3. (July 1992), 645. 2008-01-22T22:31:58-00:00 1992 Reviews of Modern Physics 64 3 645 American Physical Society colloids polymers http://www.citeulike.org/user/sas/article/1576990 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 1. (2007)</i><br /><br />Brownian dynamics simulations are used to study highly entangled solutions of semiflexible polymers. Bending fluctuations of semiflexible rods are significantly affected by entanglement only above a concentration c**, where c**~103L−3 for chains of length L similar to their persistence length. For c>c**, the tube radius Re approaches a dependence Rec−3/5 and the linear viscoelastic response develops an elastic plateau that is absent for c<c**. Experiments on isotropic solutions of F-actin are shown to span concentrations near c** for which the predicted asymptotic scaling of the plateau modulus, Gc7/5, is not yet valid. Simulations of dynamics and viscoelasticity in highly entangled solutions of semiflexible rods Shriram Ramanathan David Morse doi:10.1103/PhysRevE.76.010501 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 76, No. 1. (2007) 2007-08-20T15:00:51-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 76 1 APS actin polymers semiflexible http://www.citeulike.org/user/sas/article/1415646 <i>Rheologica Acta, Vol. 46, No. 2. (18 December 2006), pp. 297-303.</i><br /><br />Abstract We present simulations of branched polymer dynamics based on a sliplink network model, which also accounts for topological change around branch points, i.e., for branch-point diffusion. It is well-known that, with the exception of stars, branched polymers may show a peculiar rheological behavior due to the exceptionally slow relaxation of the backbone chains bridging branch points. Though Brownian simulations based on sliplinks are powerful tools to study the motion of polymers and to predict rheological properties, none of the existing methods can simulate the relaxation of the bridge chains. The reason for that is lack of a rule for network topology rearrangement around branch points, so that entanglements between bridge chains cannot be renewed. Therefore, we introduce in this paper one possible branch-point mobility rule into our primitive chain network model. For star polymers, diffusion coefficients were calculated and compared with experiments. For both star and H-shaped polymers, diffusion was simulated both with and without the new rule, and the effect on linear viscoelasticity was also determined in one case. Primitive chain network simulations for branched polymers Yuichi Masubuchi Giovanni Ianniruberto Francesco Greco Giuseppe Marrucci doi:10.1007/s00397-006-0112-4 Rheologica Acta, Vol. 46, No. 2. (18 December 2006), pp. 297-303. 2007-06-27T10:42:49-00:00 2006 Rheologica Acta 46 2 297 303 branched naples polymers sliplink http://www.citeulike.org/user/sas/article/1417078 <i>Physical Review Letters, Vol. 85, No. 12. (2000), 2522.</i><br /><br />We map dilute or semidilute solutions of nonintersecting polymer chains onto a fluid of “soft” particles interacting via a concentration dependent effective pair potential; by inverting the pair distribution function of the centers of mass of the initial polymer chains. A similar inversion is used to derive an effective wall-polymer potential; these potentials are combined to successfully reproduce the calculated exact depletion interaction induced by nonintersecting polymers between two walls. The mapping opens up the possibility of large-scale simulations of polymer solutions in complex geometries. Can Polymer Coils Be Modeled as "Soft Colloids"? AA Louis PG Bolhuis JP Hansen EJ Meijer doi:10.1103/PhysRevLett.85.2522 Physical Review Letters, Vol. 85, No. 12. (2000), 2522. 2007-06-27T17:12:32-00:00 2000 Physical Review Letters 85 12 2522 American Physical Society coils colloids polymers soft http://www.citeulike.org/user/samjlord/article/957678 <i>J. Phys. Chem. B (22 November 2006)</i> Diffusion and Viscosity in a Crowded Environment: from Nano- to Macroscale J Szymanski A Patkowski A Wilk P Garstecki R Holyst doi:10.1021/jp0666784 J. Phys. Chem. B (22 November 2006) 2006-11-22T16:38:55-00:00 2006 J. Phys. Chem. B biophysics polymers printed review http://www.citeulike.org/user/samjlord/article/2386828 <i>Science, Vol. 264, No. 5160. (6 May 1994), pp. 819-822.</i><br /><br />Tube-like motion of a single, fluorescently labeled molecule of DNA in an entangled solution of unlabeled lambda-phage DNA molecules was observed by fluorescence microscopy. One end of a 16- to 100-micrometer-long DNA was attached to a 1-micrometer bead and moved with optical tweezers. The molecule was stretched into various conformations having bends, kinks, and loops. As the polymer relaxed, it closely followed a path defined by its initial contour. The relaxation time of the disturbance caused by the bead was roughly 1 second, whereas tube-like motion in small loops persisted for longer than 2 minutes. Tube deformation, constraint release, and excess chain segment diffusion were also observed. These observations provide direct evidence for several key assumptions in the reptation model developed by de Gennes, Edwards, and Doi. 10.1126/science.8171335 Direct observation of tube-like motion of a single polymer chain TT Perkins DE Smith S Chu doi:10.1126/science.8171335 Science, Vol. 264, No. 5160. (6 May 1994), pp. 819-822. 2008-02-15T16:51:38-00:00 1994 Science 264 5160 819 822 dna polymers http://www.citeulike.org/user/samjlord/article/2923946 <i>J. Am. Chem. Soc. (24 June 2008)</i><br /><br />Abstract: We demonstrate a novel and powerful method to study electrogenerated chemiluminescence (ECL) of single nanoparticles (NPs) (r = 25 15 nm) of a conjugated polymer, F8BT, on an ITO electrode in the presence of a co-reactant, such as tri-n-propylamine (TPrAH) in acetonitrile solution. The results reveal that the maximum formation rate of ECL of individual NPs is achieved after a long build-up time (1040 s after pulse application). The high number of detected ECL photons from individual NPs (1500 photons during 100 s) highlights the potential of this technique as a very sensitive analytical method. Additionally, TPrAH acts as a very efficient protecting agent against irreversible electrochemical processes occurring in F8BT, as found in photoluminescence studies. This protection mechanism probably involves the neutralization of holes at the particle surface via electron transfer by both TPrAH and TPrA radical (TPrA"). Electrogenerated Chemiluminescence of Single Conjugated Polymer Nanoparticles Ya-Lan Chang Rodrigo Palacios Fu-Ren Fan Allen Bard Paul Barbara doi:10.1021/ja803454x J. Am. Chem. Soc. (24 June 2008) 2008-06-24T16:07:18-00:00 2008 J. Am. Chem. Soc. chemiluminescence polymers sms http://www.citeulike.org/user/samjlord/article/929940 <i>Physical Review Letters, Vol. 97, No. 18. (2006)</i><br /><br />Large step shear experiments revealed through particle tracking velocimetry that entangled polymeric liquids display either internal macroscopic movements upon shear cessation or rupturelike behavior during shear. Visible inhomogeneous motions were detected in five samples with the number of entanglements per chain ranging from 20 to 130 at amplitudes of step strain as low as 135%. Nonquiescent Relaxation in Entangled Polymer Liquids after Step Shear Shi Wang Sham Ravindranath Pouyan Boukany Michael Olechnowicz Roderic Quirk Adel Halasa Jimmy Mays doi:10.1103/PhysRevLett.97.187801 Physical Review Letters, Vol. 97, No. 18. (2006) 2006-11-06T05:09:47-00:00 2006 Physical Review Letters 97 18 APS polymers http://www.citeulike.org/user/samjlord/article/929870 <i>Macromolecules, Vol. 37, No. 11. (1 June 2004), pp. 4235-4240.</i> Tadpole Conformation of Gradient Polymer Brushes SJ Lord SS Sheiko I Larue HI Lee K Matyjaszewski doi:10.1021/ma035989z Macromolecules, Vol. 37, No. 11. (1 June 2004), pp. 4235-4240. 2006-11-06T03:54:12-00:00 2004 Macromolecules 37 11 4235 4240 polymers http://www.citeulike.org/user/samjlord/article/2466947 <i>Journal of Membrane Science, Vol. 81, No. 1-2. (16 June 1993), pp. 15-22.</i><br /><br />The permeability of 17 different 6FDA polyimides membranes to CO2 and CH4 has been determined at 25[degree sign]C and at an applied pressue of 4.87 atm. Dielectric constants g of polyimides were measured with 1 MHz frequency at 23[degree sign]C and at 55% rh (relative humidity). Fractional free volumes and dielectric constants were also obtained by theoretical calculation for comparison. Good correlation between dielectric constant and gas permeability was observed. Since the dielectric constant is a function of molar polarization and molar volume, polymer structure can be much better characterized by using [epsilon] than by using the fractional free volume. Good relationships between gas permeability and the solubility parameter and the cohesive energy density were also found. It was found that the gas permeability of the polymer can be estimated by measuring the dielectric constant, due to the correlation between [epsilon] and the gas permeability in common commercially available polymers. The dielectric constant can be applied to identify the structural factors that will lead to the preparation of polymer membranes that exhibit both a high permeability and permselectivity toward specific gases. Gas permeation of aromatic polyimides. I. Relationship between gas permeabilities and dielectric constants Kenji Matsumoto Ping Xu Tadashi Nishikimi doi:10.1016/0376-7388(93)85027-T Journal of Membrane Science, Vol. 81, No. 1-2. (16 June 1993), pp. 15-22. 2008-03-04T18:51:36-00:00 1993 Journal of Membrane Science 81 1-2 15 22 polymers http://www.citeulike.org/user/samjlord/article/1044886 <i>Macromolecules, Vol. 39, No. 23. (14 November 2006), pp. 8121-8127.</i><br /><br />Abstract: Functionalized perylene derivatives were synthesized with one or two alkoxyamine units. These compounds were used as initiators in the well-controlled living radical polymerization of isoprene, resulting in polymers with a perylene dye located at either the middle or end of the polymer. Using this approach, polyisoprenes were prepared with similar molecular weights, low polydispersities, and very good initiator efficiencies. Labeled chains were imaged on the single-molecule level in hosts of unlabeled polymer with similar composition. On the time scale from 0.2 to 2-5 s no difference between center- and end-positioned dyes was observed, suggesting that the dynamics outside of this time range should be studied. However, the most rigid host material led to the longest observed correlation times and the highest fraction of fluorophores that exhibited blinking behavior. Well-Controlled Living Polymerization of Perylene-Labeled Polyisoprenes and Their Use in Single-Molecule Imaging GT Gavranovic S Csihony NB Bowden CJ Hawker RM Waymouth WE Moerner GG Fuller doi:10.1021/ma0612475 Macromolecules, Vol. 39, No. 23. (14 November 2006), pp. 8121-8127. 2007-01-16T22:50:32-00:00 2006 Macromolecules 39 23 8121 8127 polymers sms http://www.citeulike.org/user/samjlord/article/936495 <i>J. Phys. Chem. B (8 November 2006)</i> External Electric Field Effects on Fluorescence of Pyrene Butyric Acid in a Polymer Film: Concentration Dependence and Temperature Dependence AM Ara T Iimori T Yoshizawa T Nakabayashi N Ohta doi:10.1021/jp063865t J. Phys. Chem. B (8 November 2006) 2006-11-08T16:09:32-00:00 2006 J. Phys. Chem. B photophysics polymers http://www.citeulike.org/user/samjlord/article/958144 <i>Physical Review Letters, Vol. 97, No. 21. (2006)</i><br /><br />Using single molecule spectroscopy, we show that the fluorescence lifetime trajectories of single probe molecules embedded in a glass-forming polymer melt exhibit strong fluctuations of a hopping character. Using molecular dynamics simulations targeted to explain these experimental observations, we show that the lifetime fluctuations correlate strongly with the average square displacement function of the matrix particles. The latter observable is a direct probe of the meta-basin transitions in the potential energy landscape of glass-forming liquids. We thus show here that single molecule experiments can provide detailed microscopic information on system properties that hitherto have been accessible via computer simulations only. Fluorescence Lifetime of a Single Molecule as an Observable of Meta-Basin Dynamics in Fluids Near the Glass Transition RAL Vallee M Van der Auweraer W Paul K Binder doi:10.1103/PhysRevLett.97.217801 Physical Review Letters, Vol. 97, No. 21. (2006) 2006-11-22T22:13:12-00:00 2006 Physical Review Letters 97 21 APS polymers sms http://www.citeulike.org/user/samjlord/article/945510 <i>Macromolecules, Vol. 35, No. 21. (8 October 2002), pp. 8122-8125.</i> Synthesis of Fluorescently Labeled Polymers and Their Use in Single-Molecule Imaging NB Bowden KA Willets WE Moerner RM Waymouth doi:10.1021/ma020780r Macromolecules, Vol. 35, No. 21. (8 October 2002), pp. 8122-8125. 2006-11-16T02:08:57-00:00 2002 Macromolecules 35 21 8122 8125 dcdhf polymers sms http://www.citeulike.org/user/rubendrr/article/388974 <i>J Math Biol, Vol. 40, No. 1. (January 2000), pp. 64-96.</i><br /><br />We investigate the polymerization kinetics of rod-like polymer filaments interacting with a distribution of monomer in one spatial dimension (e.g. along a narrow tube). We consider a variety of possible cases, including competition by the filament tips for the available monomer, and behaviour analogous to "treadmilling" in which the polymer adds subunits to one end and loses them at the other end so as to maintain a constant length. Applications to biological polymers such as actin filaments and microtubules are discussed. Models for spatial polymerization dynamics of rod-like polymers. L Edelstein-Keshet GB Ermentrout J Math Biol, Vol. 40, No. 1. (January 2000), pp. 64-96. 2005-11-11T17:06:04-00:00 2000 J Math Biol 0303-6812 40 1 64 96 dynamics modelling polymers http://www.citeulike.org/user/rolayo/article/2877838 <i>Polymer, Vol. In Press, Accepted Manuscript</i> Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers Chen Xu Kohji Ohno Vincent Ladmiral Russell Composto doi:10.1016/j.polymer.2008.05.040 Polymer, Vol. In Press, Accepted Manuscript 2008-06-09T18:26:00-00:00 Polymer In Press, Accepted Manuscript nanoparticles polymers http://www.citeulike.org/user/rolayo/article/2789721 <i>Polymer, Vol. In Press, Accepted Manuscript</i> Polymers with Aligned Carbon Nanotubes: Active Composite Materials SV Ahir YY Huang EM Terentjev doi:10.1016/j.polymer.2008.05.005 Polymer, Vol. In Press, Accepted Manuscript 2008-05-12T15:18:26-00:00 Polymer In Press, Accepted Manuscript carbon_nanotubes polymers http://www.citeulike.org/user/Pascalichouchou/article/2330327 <i>Water Research, Vol. 36, No. 16. (September 2002), pp. 3941-3948.</i><br /><br />Sewers are typically a means of transporting wastewater to a treatment facility, with little biotransformation of the soluble polymeric organic matter by suspended biomass. In the interest of providing an effective pretreatment of wastewater in a sewer network, it is necessary to design an accurate tool simulating sewer conditions and introduce an appropriate biomass for macromolecular pollutant degradation. Such a model reactor was built using a tanks-in-series design and the degradation of a polysaccharide (starch) by Aspergillus niger MUCL 28817 was studied. Starch degradation and the accumulation of intermediates (hydrolysis fragments) in the individual reactors were quantified under transient conditions, at a mean hydraulic residence time of 17 h. Starch was degraded by 90% in this reactor system and an accumulation of oligosaccharides with molecular weight lower than 1000 Da was observed. These results may be helpful in the development of wastewater treatment in sewers and in the alleviation of the burden on undersized wastewater treatment systems. A tanks-in-series bioreactor to simulate macromolecule-laden wastewater pretreatment under sewer conditions by Aspergillus niger Lacina Coulibaly Henry Naveau Spiros Agathos doi:10.1016/S0043-1354(02)00117-3 Water Research, Vol. 36, No. 16. (September 2002), pp. 3941-3948. 2008-02-04T18:47:46-00:00 2002 Water Research 36 16 3941 3948 decentralisation hydrolysis macromolecules polymers sewer starch wwtp http://www.citeulike.org/user/Pascalichouchou/article/2330257 <i>Water Research, Vol. 32, No. 1. (January 1998), pp. 31-38.</i><br /><br />Macromolecular compounds such as proteins and polysaccharides can comprise a significant portion of dissolved organic carbon in wastewater, but limited information is available on how these compounds are degraded in biological wastewater treatment systems. Bacteria cannot assimilate intact macromolecules but must first hydrolyze them to monomers or small oligomers. Whether this hydrolysis occurs in contact with cells or by enzymes released into bulk solution is critical to an understanding of macromolecule metabolism. This study used the fluorescent model substrate analogs -leucine-7-amido-4-methylcoumarin[middle dot]HCl (Leu-MCA) and 4-methylumbelliferyl-[alpha]-glucoside (MUF-[alpha]-glc) to determine the location of leucine aminopeptidase and [alpha]-glucosidase activity in wastewater inoculated biofilm and suspended cultures and in trickling filter effluent. In biofilm cultures, no more than 3% of total hydrolytic activity was located in the cell-free bulk solution. Similar results were obtained in suspended culture where 97% of leucine aminopeptidase and 93% of [alpha]-glucosidase activity occurred in contact with cells. In trickling filter effluent, hydrolysis was also predominantly cell-associated. Hydrolysis rates were at least five times higher in contact with cells and sloughed biofilm pieces than in cell-free solution. When considered with the results of other experiments demonstrating that hydrolytic fragments of proteins and polysaccharides accumulate in bulk solution during macromolecule degradation, these experiments support a generalized mechanism for macromolecule degradation that features cell-associated hydrolysis followed by the release of hydrolytic fragments back into bulk solution. This cell-associated hydrolysis and release is repeated until hydrolytic fragments are small enough to be assimilated by cells. Use of this macromolecule degradation mechanism can help refine wastewater treatment models so that they can more accurately predict the performance of bioreactors treating complex wastewaters. (c) 1998 Elsevier Science Ltd. All rights reserved LOCATION OF PROTEIN AND POLYSACCHARIDE HYDROLYTIC ACTIVITY IN SUSPENDED AND BIOFILM WASTEWATER CULTURES David Confer Bruce Logan doi:10.1016/S0043-1354(97)00194-2 Water Research, Vol. 32, No. 1. (January 1998), pp. 31-38. 2008-02-04T18:18:49-00:00 1998 Water Research 32 1 31 38 biofilm enzymes hydrolysis macromolecules polymers http://www.citeulike.org/user/Pascalichouchou/article/2334711 <i>Water Research, Vol. 29, No. 1. (January 1995), 387.</i> Comment on "degradation of non-diffusible organic matter in biofilm reactors" by and , Wat. Res. 27, 1689-1691 (1993) Kyoung Ro doi:10.1016/0043-1354(94)E0095-N Water Research, Vol. 29, No. 1. (January 1995), 387. 2008-02-05T12:51:12-00:00 1995 Water Research 29 1 387 biofilm filter hydrolysis macromolecules particulate polymers http://www.citeulike.org/user/Pascalichouchou/article/2330059 <i>Water Research, Vol. 37, No. 3. (February 2003), pp. 485-492.</i><br /><br />The effect of degradation of polymeric substrates (starch and soy proteins mixture) on the structure of biofilms has been studied. The characteristics of the obtained biofilms were compared to those obtained on corresponding monomeric substrates (glucose and aspartic acid). Based on literature suggestions it was hypothesized that the polymeric substrates, which have a low diffusion rate in the biofilm matrix, would affect the biofilm structure if hydrolytic activity occurs in the biofilm. The obtained biofilm could be expected to present properties like low density and rough surface, facilitating transport and conversion of large polymeric molecules. From the present study it was concluded that the structure of the formed biofilms was influenced by the substrate degraded, however no unequivocal effect of degradation of a polymer on the biofilm structure could be observed. The hydrolytic activity with soy protein and starch as substrate was under stable conditions found to be mainly associated to the biofilm (more than 95% of the total activity). During unstable conditions or start-up significant hydrolytic activity occurred outside the biofilm. Degradation of polymers in a biofilm airlift suspension reactor A Mosquera-Corral A Montras JJ Heijnen MCM van Loosdrecht doi:10.1016/S0043-1354(02)00309-3 Water Research, Vol. 37, No. 3. (February 2003), pp. 485-492. 2008-02-04T17:05:23-00:00 2003 Water Research 37 3 485 492 activity biofilm hydrolysis macromolecules polymers http://www.citeulike.org/user/Pascalichouchou/article/2333857 <i>Water Research, Vol. 27, No. 11. (November 1993), pp. 1689-1691.</i><br /><br />A simple laboratory test has been developed in order to demonstrate qualitatively, that the removal of non-diffusible organics in a biofilm reactor requires hydrolysis by extracellular enzymes in the bulk water of the reactor. The results demonstrate the effect of changing volume of bulk water on the over all removal. Degradation of non-diffusible organic matter in biofilm reactors Lars Rohold Poul Harremoes doi:10.1016/0043-1354(93)90133-3 Water Research, Vol. 27, No. 11. (November 1993), pp. 1689-1691. 2008-02-05T09:02:31-00:00 1993 Water Research 27 11 1689 1691 biofilm filter hydrolysis particulate polymers http://www.citeulike.org/user/norris/article/1974486 <i>(14 August 2000)</i><br /><br /><div><div>This comprehensive introduction to principles underlying laser light scattering focuses on time dependence of fluctuations in fluid systems. It also serves as introduction to theory of time correlation functions, with chapters on projection operator techniques in statistical mechanics. Over 60 text figures. 1976 edition.<br></div></div> Dynamic Light Scattering: With Applications to Chemistry, Biology, and Physics Bruce Berne Robert Pecora (14 August 2000) 2007-11-24T19:53:59-00:00 2000 Dover Publications polymers http://www.citeulike.org/user/norris/article/1551703 <i>Mathematics and Mechanics of Solids, Vol. 10, No. 2. (1 April 2005), pp. 167-181.</i><br /><br />Constitutive equations for the back stress in amorphous glassy polymers based on extended forms of the non-Gaussian James--Guth 3-chain and Arruda--Boyce 8-chain models of rubber elasticity are derived from the extended Wu and van der Giessen non-Gaussian full-network model. A simple and invariant constitutive equation for the back stress tensor is then derived from the Wu and van der Giessen model by an average-stretch approximation. Although the average-stretch model of the full-network amorphous microstructure is more general than other chain cell models, the constitutive equation is the same as the 8-chain back stress relation. Back stress equations for a class of extended phenomenological models, including the Gent material model, are described. 10.1177/1081286505036316 Constitutive Equations for the Back Stress in Amorphous Glassy Polymers Millard Beatty doi:10.1177/1081286505036316 Mathematics and Mechanics of Solids, Vol. 10, No. 2. (1 April 2005), pp. 167-181. 2007-08-10T13:31:03-00:00 2005 Mathematics and Mechanics of Solids 10 2 167 181 elasticity polymers http://www.citeulike.org/user/norris/article/1885540 <i>Mathematics and Mechanics of Solids (14 May 2007), 1081286507076405.</i><br /><br />The response function for a general class of elastic molecular based materials characterized by their limiting molecular chain extensibility and depending on only the first principal invariant of the Cauchy-Green deformation tensor together with a certain molecular based limiting extensibility parameter is introduced. The constitutive response function for the Gent material is then derived inversely as the [0/1] Pade approximant of this class, a result that leads naturally to an infinite geometric series representation of its response function. Truncation of this series function characterizes a familiar class of quadratic materials now having physically relevant material constants. It is shown that the [0/2] approximant of the response function for the general class of restricted elastic materials leads inversely to a new constitutive model and its series representation. Of course, many familiar limited elastic material models are members of the general class. The Pade approximants for some response functions are not, and empirical modifications that admit these as members of the general class are described. Examples of two limited elastic models in the class that are not Pade approximants are noted. The strain energy functions for a few of the restricted elastic models described are presented. 10.1177/1081286507076405 On Constitutive Models for Limited Elastic, Molecular Based Materials Millard Beatty doi:10.1177/1081286507076405 Mathematics and Mechanics of Solids (14 May 2007), 1081286507076405. 2007-11-08T17:57:38-00:00 2007 Mathematics and Mechanics of Solids 1081286507076405 polymers http://www.citeulike.org/user/norris/article/1670099 <i>Science, Vol. 317, No. 5838. (3 August 2007), pp. 650-653.</i><br /><br />A freely floating polymer film, tens of nanometers in thickness, wrinkles under the capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of the wrinkles. The dependence of the number of wrinkles on the elastic properties of the film and on the capillary force exerted by the drop confirms recent theoretical predictions on the selection of a pattern with a well-defined length scale in the wrinkling instability. We combined scaling relations that were developed for the length of the wrinkles with those for the number of wrinkles to construct a metrology for measuring the elasticity and thickness of ultrathin films that relies on no more than a dish of fluid and a low-magnification microscope. We validated this method on polymer films modified by plasticizer. The relaxation of the wrinkles affords a simple method to study the viscoelastic response of ultrathin films. 10.1126/science.1144616 Capillary Wrinkling of Floating Thin Polymer Films Jiangshui Huang Megan Juszkiewicz Wim de Jeu Enrique Cerda Todd Emrick Narayanan Menon Thomas Russell doi:10.1126/science.1144616 Science, Vol. 317, No. 5838. (3 August 2007), pp. 650-653. 2007-09-18T19:02:24-00:00 2007 Science 317 5838 650 653 polymers http://www.citeulike.org/user/norris/article/1611074 <i>International Journal of Solids and Structures, Vol. 42, No. 5-6. (March 2005), pp. 1547-1559.</i><br /><br />We study a class of models that describes isotropic hyperelastic materials and that is defined using a novel set of invariants for the Hencky strain. For these models, we derive the appropriate form of the Baker-Ericksen inequalities. To illustrate an application, we then use this form of the Baker-Ericksen inequalities to develop a set of specific constitutive restrictions for a model of rubber-like materials proposed in [Criscione, J.C., Humphrey, J.D., Douglas, A.S., Hunter, W.C., 2000. J. Mech. Phys. Solids 48, 2445-2465]. The Baker-Ericksen inequalities for hyperelastic models using a novel set of invariants of Hencky strain Patrick Wilber John Criscione doi:10.1016/j.ijsolstr.2004.08.001 International Journal of Solids and Structures, Vol. 42, No. 5-6. (March 2005), pp. 1547-1559. 2007-08-31T18:35:47-00:00 2005 International Journal of Solids and Structures 42 5-6 1547 1559 elasticity electrostriction polymers http://www.citeulike.org/user/norris/article/1597318 <i>Journal of Elasticity, Vol. 13, No. 3. (1983), pp. 317-344.</i><br /><br />The nearly constant pitch of the sound radiated by a sufficiently stretched rubber cord, a phenomenon observed independently by two experimenters at the turn of the century, is explained analytically for three ideal rubberlike material models. Transverse vibrational frequency data for three kinds of rubber strings, obtained with the aid of a novel laser apparatus, are compared with the analytical results. A numerical scheme is introduced to compute from the experimental data the apparent average number of links in a molecular chain of a rubberlike material from both simple tension and transverse frequency measurements. It is shown that the nearly flat frequency response is a molecular network finite extensibility effect that is controlled by the apparent number of links in a chain of the molecular network structure. On the transverse vibration of a rubber string Millard Beatty Alan Chow doi:10.1007/BF00043000 Journal of Elasticity, Vol. 13, No. 3. (1983), pp. 317-344. 2007-08-27T21:13:38-00:00 1983 Journal of Elasticity 13 3 317 344 elasticity nonlinear polymers http://www.citeulike.org/user/norris/article/2574678 <i>Applied Physics Letters, Vol. 90, No. 8. (2007)</i><br /><br />View this record in Web of Science Energy minimization for self-organized structure formation and actuation Guggi Kofod Werner Wirges Mika Paajanen Siegfried Bauer Applied Physics Letters, Vol. 90, No. 8. (2007) 2008-03-23T14:19:53-00:00 2007 Applied Physics Letters 90 8 AIP polymers http://www.citeulike.org/user/norris/article/1885785 <i>Mathematics and Mechanics of Solids, Vol. 7, No. 4. (1 August 2002), pp. 353-371.</i><br /><br />Many rubber-like materials and soft tissues exhibit a significant stiffening or hardening in their stress-strain curves at large strains. The accurate modelling of this phenomenon is a key issue for a better understanding of the thermomechanics of rubber and the biomechanics of arteries, blood vessels, tendons and other biological tissues. In this paper, we consider several strain-energy functions that have been proposed to model this strain hardening effect in the framework of the theory of isotropic hyperelasticity. These models may be divided in two main families: power law models and limiting chain extensibility models, both of which are based on non-Gaussian statistics for their molecular structure. The known limiting chain extensibility models involve a constraint on the strain invariants. Here we consider alternative models which limit the maximum stretch. The two homogeneous deformations of uniaxial extension and pure shear are examined in detail. It is shown that simple modifications of the incompressible neo-Hookean or Varga materials to reflect limiting chain extensibility can be used to match well with the classic experimental data of Treloar. Some remarks on empirical inequalities and ellipticity are also given. 10.1177/108128028477 Constitutive Modelling of Rubber-Like and Biological Materials with Limiting Chain Extensibility Cornelius Horgan Giuseppe Saccomandi doi:10.1177/108128028477 Mathematics and Mechanics of Solids, Vol. 7, No. 4. (1 August 2002), pp. 353-371. 2007-11-08T19:15:44-00:00 2002 Mathematics and Mechanics of Solids 7 4 353 371 elasticity polymers http://www.citeulike.org/user/monkare/article/2460940 <i>Journal of Pharmaceutical Sciences, Vol. 97, No. 1. (2008), pp. 71-87.</i><br /><br />Poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) microspheres and nanoparticles remain the focus of intensive research effort directed to the controlled release and in vivo localization of drugs. In recent years engineering approaches have been devised to create novel micro- and nano-particles which provide greater control over the drug release profile and present opportunities for drug targeting at the tissue and cellular levels. This has been possible with better understanding and manipulation of the fabrication and degradation processes, particularly emulsion-solvent extraction, and conjugation of polyesters with ligands or other polymers before or after particle formation. As a result, particle surface and internal porosity have been designed to meet criteria-facilitating passive targeting (e.g., for pulmonary delivery), modification of the drug release profile (e.g., attenuation of the burst release) and active targeting via ligand binding to specific cell receptors. It is now possible to envisage adventurous applications for polyester microparticles beyond their inherent role as biodegradable, controlled drug delivery vehicles. These may include drug delivery vehicles for the treatment of cerebral disease and tumor targeting, and codelivery of drugs in a pulsatile and/or time-delayed fashion. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:71-87, 2008 Engineering biodegradable polyester particles with specific drug targeting and drug release properties Farahidah Mohamed Christopher van der Walle doi:10.1002/jps.21082 Journal of Pharmaceutical Sciences, Vol. 97, No. 1. (2008), pp. 71-87. 2008-03-03T14:22:54-00:00 2008 Journal of Pharmaceutical Sciences 97 1 71 87 drug_delivery drug_targeting microparticles nanoparticles polyesters polymers review http://www.citeulike.org/user/monkare/article/2905020 <i>Biomaterials, Vol. 17, No. 2. (January 1996), pp. 103-114.</i><br /><br />The most important features of the degradation and erosion of degradable polymers in vitro are discussed. Parameters of chemical degradation, which is the scission of the polymer backbone, are described such as the type of polymer bond, pH and copolymer composition. Examples are given how these parameters can be used to control degradation rates. Degradation leads finally to polymer erosion, the loss of material from the polymer bulk. The resulting changes in morphology, pH, oligomer and monomer properties as well as crystallinity are illustrated with selected examples. Finally, a brief survey on approaches to polymer degradation and erosion is given. Mechanisms of polymer degradation and erosion Achim Göpferich doi:10.1016/0142-9612(96)85755-3 Biomaterials, Vol. 17, No. 2. (January 1996), pp. 103-114. 2008-06-18T10:38:41-00:00 1996 Biomaterials 17 2 103 114 degradation erosion modelling polymers http://www.citeulike.org/user/monkare/article/2484030 <i>Proceedings of the National Academy of Sciences, Vol. 90, No. 2. (15 January 1993), pp. 552-556.</i><br /><br />10.1073/pnas.90.2.552 Erosion Kinetics of Hydrolytically Degradable Polymers JA Tamada R Langer doi:10.1073/pnas.90.2.552 Proceedings of the National Academy of Sciences, Vol. 90, No. 2. (15 January 1993), pp. 552-556. 2008-03-07T13:21:19-00:00 1993 Proceedings of the National Academy of Sciences 90 2 552 556 degradation erosion kinetics polymers http://www.citeulike.org/user/monkare/article/2887016 <i>International Journal of Pharmaceutics, Vol. 163, No. 1-2. (18 March 1998), pp. 123-131.</i><br /><br />The determination of gel layer thickness and the velocity of front movement in Hydroxypropylmethylcellulose (HPMC) matrices which contain both a freely and a poorly soluble drug, respectively, is described. A new method based on the measurement of backscattered ultrasound signals has been developed for characterizing advancement of eroding front. The advantage of the ultrasound method is the possibility of continuous measurements. Our investigations indicate that both methods achieve nearly the same result. Matrices with pholedrine sulphate showed greater movements of the eroding front compared to matrices with chloramphenicol, whereas the movement of the swelling front was almost the same in each case. The drug release is dependent on the solubility of the drug, therefore the diffusion of the drug through the gel and therefore the position of the diffusion front in the gelling zone can be considered a possible descriptor of drug release from HPMC matrices. The use of ultrasound and penetrometer to characterize the advancement of swelling and eroding fronts in HPMC matrices R Konrad A Christ G Zessin U Cobet doi:10.1016/S0378-5173(97)00375-X International Journal of Pharmaceutics, Vol. 163, No. 1-2. (18 March 1998), pp. 123-131. 2008-06-12T11:11:42-00:00 1998 International Journal of Pharmaceutics 163 1-2 123 131 polymers ultrasound http://www.citeulike.org/user/monkare/article/2898882 <i>Advanced Drug Delivery Reviews, Vol. 54, No. 9. (5 November 2002), pp. 1225-1235.</i><br /><br />The ability to deliver therapeutic agents to a patient in a pulsatile or staggered release profile has been a major goal in drug delivery research over the last two decades. This review will cover methods that have been developed to control drug delivery profiles with implantable polymeric systems. Externally and internally controlled systems will be discussed, spanning a range of technologies that include pre-programmed systems, as well as systems that are sensitive to modulated enzymatic or hydrolytic degradation, pH, magnetic fields, ultrasound, electric fields, temperature, light and mechanical stimulation. Implantable systems have the potential to improve the quality of life for patients undergoing therapy with a variable dosing regime by eliminating the need for multiple intravenous injections. Ideally, these systems would also result in increased patient compliance with a given therapy due to the relative ease of self-dosing. Implantable, polymeric systems for modulated drug delivery S Sershen J West doi:10.1016/S0169-409X(02)00090-X Advanced Drug Delivery Reviews, Vol. 54, No. 9. (5 November 2002), pp. 1225-1235. 2008-06-16T15:19:11-00:00 2002 Advanced Drug Delivery Reviews 54 9 1225 1235 drug_delivery implants polymers review http://www.citeulike.org/user/mikaellund/article/3129785 <i>Biophys. J., Vol. 95, No. 3. (1 August 2008), pp. 1285-1294.</i><br /><br />The solubility of aqueous solutions of lysozyme in the presence of polyethylene glycol and various alkaline salts was studied experimentally. The protein-electrolyte mixture was titrated with polyethylene glycol, and when precipitation of the protein occurred, a strong increase of the absorbance at 340 nm was observed. The solubility data were obtained as a function of experimental variables such as protein and electrolyte concentrations, electrolyte type, degree of polymerization of polyethylene glycol, and pH of the solution; the last defines the net charge of the lysozyme. The results indicate that the solubility of lysozyme decreases with the addition of polyethylene glycol; the solubility is lower for a polyethylene glycol with a higher degree of polymerization. Further, the logarithm of the protein solubility is a linear function of the polyethylene glycol concentration. The process is reversible and the protein remains in its native form. An increase of the electrolyte (NaCl) concentration decreases the solubility of lysozyme in the presence and absence of polyethylene glycol. The effect can be explained by the screening of the charged amino residues of the protein. The solubility experiments were performed at two different pH values (pH = 4.0 and 6.0), where the lysozyme net charge was +11 and +8, respectively. Ion-specific effects were systematically investigated. Anions such as Br-, Cl-, F-, and [IMG]f1.gif" ALT="Formula" BORDER="0"> (all in combination with Na+), when acting as counterions to a protein with positive net charge, exhibit a strong effect on the lysozyme solubility. The differences in protein solubility for chloride solutions with different cations Cs+, K+, and Na+ (coions) were much smaller. The results at pH = 4.0 show that anions decrease the lysozyme solubility in the order [IMG]f2.gif" ALT="Formula" BORDER="0"> (the inverse Hofmeister series), whereas cations follow the direct Hofmeister series (Cs+ < K+ < Na+) in this situation. 10.1529/biophysj.108.128694 Solubility of Lysozyme in Polyethylene Glycol-Electrolyte Mixtures: The Depletion Interaction and Ion-Specific Effects Matjaz Boncina Jurij Rescic Vojko Vlachy doi:10.1529/biophysj.108.128694 Biophys. J., Vol. 95, No. 3. (1 August 2008), pp. 1285-1294. 2008-08-17T13:52:31-00:00 2008 Biophys. J. 95 3 1285 1294 aggregation hofmeister polymers protein http://www.citeulike.org/user/majdula/article/2734753 <i>Molecular Physics, Vol. 101, No. 16. (2003), pp. 2575-2600.</i><br /><br />The aim of the work presented in this paper is to help in the understanding of the lower critical solution temperature (LCST) fluid phase behaviour exhibited by polymer solutions. It is well recognized that the LCST in polymer solutions is a consequence of density (compressibility) effects; the solvent is much more compressible than the polymer and the increasing difference in compressibility when the temperature is increased leads to a negative volume of mixing. The separate roles that the repulsive and attractive intermolecular interactions play in this regard are less well understood. In this study we use the Wertheim first-order thermodynamic perturbation theory (TPT1) [Wertheim, M.S., 1987, J. chem. Phys., 87, 7323; Chapman, W. G., Jackson, G., and Gubbins, K. E., 1988, Molec. Phys., 65, 1057] to describe the phase equilibria of model polymer solutions of hard spheres and hard-sphere chains where the diameter of the solvent and the polymeric segments are the same (symmetrical system). The thermodynamic functions (volume, enthalpy, entropy and Gibbs function) of mixing are determined to assess the possibility of a demixing instability in such a system. No fluid-fluid phase separation is found for the purely repulsive (athermal) system, regardless of the chain length of the polymer. The role of the attractive interactions is then investigated by incorporating attractive interactions at the mean-field level; the simplest system with equivalent (symmetric) solvent-solvent, solvent-polymer segment, and polymer segment-polymer segment interaction energies is examined. The attractive interactions are found to be essential in describing the liquid-liquid phase separation; LCST behaviour is found for mixtures with 'polymer' chains of seven segments or more. In this case we show that the phase behaviour is driven by an unfavourable (negative) entropy of mixing due to an increase in the density of the solvent on addition of small amounts of polymer. We also determine the thermodynamic properties of mixing for a system of spherical molecules of the same size with directional interactions that give rise to LCST and closed-loop behaviour. As expected the mechanism for phase separation in such systems is very different to that in polymer solutions. Understanding liquid-liquid immiscibility and LCST behaviour in polymer solutions with a Wertheim TPT1 description P Paricaud A Galindo G Jackson Molecular Physics, Vol. 101, No. 16. (2003), pp. 2575-2600. 2008-04-29T15:51:37-00:00 2003 Molecular Physics 101 16 2575 2600 demixing lcst lle mechanism polymers wertheim http://www.citeulike.org/user/majdula/article/2625777 <i>Z. Naturforsch. Sect. A J. Phys. Sci., Vol. 62, No. 5-6. (2007), pp. 275-280.</i><br /><br />Ionic liquids represent a unique class of solvents that offer unprecedented versatility and tunability. Nature has developed a wide variety of materials based upon both proteins and polysaccharides. Many of these materials have unique properties that are a function not only of the material identity but are also largely dictated by processing conditions. Recent work has shown the potential of ionic liquids as solvents for the dissolution and processing of biopolymers. In this research we have expanded upon the limited data available to date using several biopolymers including: silk, chitin, collagen and elastin. © 2007 Verlag der Zeitschrift fu?r Naturforschung. Dissolution of biopolymers using ionic liquids RA Mantz DM Fox Green PA Fylstra HC De Long PC Trulove Z. Naturforsch. Sect. A J. Phys. Sci., Vol. 62, No. 5-6. (2007), pp. 275-280. 2008-04-03T11:12:09-00:00 2007 Z. Naturforsch. Sect. A J. Phys. Sci. 62 5-6 275 280 ionic liquids polymers solubility http://www.citeulike.org/user/majdula/article/2002455 <i>AIChE Journal, Vol. 50, No. 10. (2004), pp. 2439-2454.</i><br /><br />In this work the suitability of selected commercially available hyperbranched polymers and ionic liquids as entrainers for the extractive distillation and as extraction solvents for the liquid-liquid extraction is investigated. Based on thermodynamic studies on the influence of hyperbranched polymers and ionic liquids on the vapor-liquid and liquid-liquid equilibrium of the azeotropic ethanol-water and THF-water systems, process simulations are carried out, which allow evaluating the potential of hyperbranched polymers and ionic liquids as selective components for the mentioned applications in terms of feasibility and energetic efficiency. Both hyperbranched polymers and ionic liquids break a variety of azeotropic systems. Since their selectivity, capacity, viscosity, and thermal stability can be customized, they appear superior to many conventional entrainers and extraction solvents. For the ethanol-water separation, the nonvolatile substances hyperbranched polyglycerol and [EMIM]+[BF4]- show a remarkable entrainer performance and therefore enable extractive distillation processes, which require less energy than the conventional process using 1,2-ethanediol as an entrainer. Evaluation of a new THF-water separation process indicates the competitiveness of the suggested process and a considerable potential of using hyperbranched polymers as extraction solvents. © 2004 American Institute of Chemical Engineers AIChE J 50: 2439-2454, 2004 Separation of azeotropic mixtures using hyperbranched polymers or ionic liquids Matthias Seiler Carsten Jork Asimina Kavarnou Wolfgang Arlt Rolf Hirsch doi:10.1002/aic.10249 AIChE Journal, Vol. 50, No. 10. (2004), pp. 2439-2454. 2007-11-28T09:49:54-00:00 2004 AIChE Journal 50 10 2439 2454 azeotrope ionic liquid polymers separation http://www.citeulike.org/user/madhadron/article/1101405 <i>Proc Natl Acad Sci U S A, Vol. 103, No. 33. (15 August 2006), pp. 12388-12393.</i><br /><br />Despite recent progress in visualization experiments, the mechanism underlying chromosome segregation in bacteria still remains elusive. Here we address a basic physical issue associated with bacterial chromosome segregation, namely the spatial organization of highly confined, self-avoiding polymers (of nontrivial topology) in a rod-shaped cell-like geometry. Through computer simulations, we present evidence that, under strong confinement conditions, topologically distinct domains of a polymer complex effectively repel each other to maximize their conformational entropy, suggesting that duplicated circular chromosomes could partition spontaneously. This mechanism not only is able to account for the spatial separation per se but also captures the major features of the spatiotemporal organization of the duplicating chromosomes observed in Escherichia coli and Caulobacter crescentus. Entropy-driven spatial organization of highly confined polymers: lessons for the bacterial chromosome. S Jun B Mulder doi:10.1073/pnas.0605305103 Proc Natl Acad Sci U S A, Vol. 103, No. 33. (15 August 2006), pp. 12388-12393. 2007-02-12T02:21:34-00:00 2006 Proc Natl Acad Sci U S A 0027-8424 103 33 12388 12393 chromosomes genetics polymers http://www.citeulike.org/user/madhadron/article/1419634 <i>Science, Vol. 276, No. 5315. (16 May 1997), pp. 1112-1116.</i><br /><br />10.1126/science.276.5315.1112 Folding-Unfolding Transitions in Single Titin Molecules Characterized with Laser Tweezers Miklos Kellermayer Steven Smith Henk Granzier Carlos Bustamante doi:10.1126/science.276.5315.1112 Science, Vol. 276, No. 5315. (16 May 1997), pp. 1112-1116. 2007-06-28T14:03:31-00:00 1997 Science 276 5315 1112 1116 polymers protein http://www.citeulike.org/user/l-alex/article/1698413 <i>Physics of Fluids, Vol. 11, No. 2. (1999), pp. 494-496.</i><br /><br />The wake behind a circular cylinder in water is visualized when colored solutions are injected through rows of holes pierced in the cylinder. When these solutions are viscoelastic, a drastic change of the shape of the wake is observed compared to that observed for water injections. The aspect ratio of the wake is decreased, the wavelength of the vortices is increased, and a large region of slow fluid motion is developed behind the cylinder. It is shown that these observations are consistent to a shear instability inhibition due to a local elasticity. ©1999 American Institute of Physics. Shear instability inhibition in a cylinder wake by local injection of a viscoelastic fluid O Cadot M Lebey doi:10.1063/1.869864 Physics of Fluids, Vol. 11, No. 2. (1999), pp. 494-496. 2007-09-26T21:55:20-00:00 1999 Physics of Fluids 11 2 494 496 AIP drag-reduction polymers vortex http://www.citeulike.org/user/l-alex/article/1168869 <i>(15 Mar 2007)</i><br /><br />The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. At late times when viscoelastic stresses become important, polymer filaments show much slower evolution, morphology featuring multiple connected drops, and different scaling with the ratio of flow rates. The filament thinning process can be described in terms of extensional viscosities of the immiscible fluids, which for the polymer solution includes strain hardening. Polymeric filament thinning and breakup in microchannels PE Arratia JP Gollub DJ Durian (15 Mar 2007) 2007-03-17T15:44:25-00:00 2007 extensional-viscosity polymers