Fri, 04 Jul 2008 23:48:10 BST CiteULike: タグ: bcp http://www.citeulike.org/tag/bcp CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/saru/article/808916 <i>Virology, Vol. 232, No. 1. (26 May 1997), pp. 167-173.</i><br /><br />Previously we have reported that the essential 3a movement gene of icosahedral cowpea chlorotic mottle virus (CCMV) can be functionally replaced by the 30-kDa movement gene of rod-shaped sunn-hemp mosaic virus (SHMV). Because plant RNA viruses differ in requiring or not requiring coat protein for systemic infection, we have now investigated whether systemic spread by this CCMV/SHMV hybrid is dependent on its CCMV coat protein as well as its SHMV movement protein. We find that either deletion or frameshift mutations in the coat protein gene block systemic spread. Thus, like wild-type CCMV, systemic infection by the hybrid is dependent on both movement protein and coat protein. These results further support the conclusion that the required functions of the coat and movement proteins in CCMV spread do not depend on sequence-specific interaction between these proteins. Additional features of the hybrid also motivated testing the effects of modulating movement protein expression. Creating an extra, out-of-frame translational start codon (AUG) shortly upstream of the 3a movement protein gene in CCMV downregulated its expression 18-fold. Nevertheless, for CCMV derivatives bearing either the CCMV 3a gene or the SHMV 30-kDa gene, the extra AUG resulted in only a minor delay in the onset of viral spread and little or no effect on the subsequent rate of cell-to-cell spread. Thus, under normal circumstances, the rate of CCMV cell-to-cell spread in cowpea plants appears to be limited primarily by factors other than movement protein synthesis. Effects of Coat Protein Mutations and Reduced Movement Protein Expression on Infection Spread by Cowpea Chlorotic Mottle Virus and Its Hybrid Derivatives Walter De Jong Kazuyuki Mise Antony Chu Paul Ahlquist doi:10.1006/viro.1997.8544 Virology, Vol. 232, No. 1. (26 May 1997), pp. 167-173. 2006-08-21T08:22:42-00:00 1997 Virology 232 1 167 173 bcp bromo http://www.citeulike.org/user/rbgrubbs/article/2795088 <i>Macromolecules, Vol. 41, No. 9. (13 May 2008), pp. 3243-3249.</i><br /><br />Abstract: This work describes the thermoresponsive transition in polystyrene-block-poly(N-isopropylacrylamide)-block-polystyrene (PS-block-PNIPAM-block-PS) triblock copolymer hydrogels, as observed by both direct and reciprocal space in-situ characterization. The hydrogel morphology was studied in both the dry and wet state, at temperatures below and beyond the coilglobule transition of PNIPAM, using vitrified ice cryo-transmission electron microscopy (cryo-TEM), in-situ freeze-drying technique, and small-angle X-ray scattering (SAXS). The selected PS-block-PNIPAM-block-PS triblock copolymers were intentionally designed in such a molecular architecture to self-assemble into spherical and bicontinuous morphology with the poly(N-isopropylacrylamide) forming the continuous matrix. The phase behavior in bulk was directly investigated by SAXS as a function of temperature, while free-standing polymer thin films of samples quenched from different temperatures, allowed observing by cryo-TEM the changes in hydrogel microstructure. Finally, sublimation of water via controlled freeze-drying in the TEM column allowed studying systems without the presence of vitrified water, which enables direct imaging of the densely connected physically cross-linked polymer network. By combining these techniques on samples exhibiting both spherical and gyroidal morphologies, it was demonstrated that (i) PNIPAM form physically connected networks in spherical structures and bicontinuous morphologies in the gyroidal phase, (ii) in PNIPAM chains strands are strongly stretched above the polymer coil-to-globule transition, and (iii) surprisingly, upon the gel swelling process, the PS domains undergo extensive plastic deformation although temperature is always maintained well below the PS glass transition bulk temperature. The possible physical mechanisms responsible for this plastic deformation can be understood in terms of the dependence of PS glass transition temperature on the size of nanometer-scaled domains. Direct Imaging of Nanoscopic Plastic Deformation below Bulk Tg and Chain Stretching in Temperature-Responsive Block Copolymer Hydrogels by Cryo-TEM Antti Nyk&#xe4;nen Markus Nuopponen Panu Hiekkataipale Sami-Pekka Hirvonen Antti Soininen Heikki Tenhu Olli Ikkala Raffaele Mezzenga Janne Ruokolainen doi:10.1021/ma702496j Macromolecules, Vol. 41, No. 9. (13 May 2008), pp. 3243-3249. 2008-05-13T13:59:10-00:00 2008 Macromolecules 41 9 3243 3249 bcp pnipa structure http://www.citeulike.org/user/rbgrubbs/article/2795493 <i>Macromolecules, Vol. 41, No. 6. (25 March 2008), pp. 2271-2277.</i><br /><br />Abstract: The phase behavior of ion-containing block copolymer membranes in equilibrium with humidified air is studied as a function of the relative humidity (RH) of the surrounding air, ion content of the copolymer, and temperature. Increasing RH at constant temperature results in both disorder-to-order and order-to-order transitions. In-situ small-angle neutron scattering experiments on the open block copolymer system, when combined with water uptake measurement, indicate that the disorder-to-order transition is driven by an increase in the partial molar entropy of the water molecules in the ordered phase relative to that in the disordered phase. This is in contrast to most systems wherein increasing entropy results in stabilization of the disordered phase. Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes MJ Park AJ Nedoma PL Geissler NP Balsara A Jackson D Cookson doi:10.1021/ma702320t Macromolecules, Vol. 41, No. 6. (25 March 2008), pp. 2271-2277. 2008-05-13T15:43:01-00:00 2008 Macromolecules 41 6 2271 2277 bcp responsive structure http://www.citeulike.org/user/katsuhide/article/587520 <i>Applied Physics Letters, Vol. 76, No. 19. (2000), pp. 2650-2652.</i><br /><br />We demonstrate a method for efficient photon harvesting in organic thin films, thereby increasing the efficiency of organic photovoltaic cells. By incorporating an exciton-blocking layer (EBL) inserted between the photoactive organic layers and the metal cathode, we achieved an external power conversion efficiency of 2.4%±0.3% in vacuum-deposited ultrathin organic bilayer photovoltaic (PV) cells employed in a simple light trapping geometry. Ultrathin (~100 Å) cells incorporating the transparent, conductive EBL have an internal quantum efficiency as high as 33%±4% over a spectral region matched to the solar spectrum. The very thin organic layers have a low series resistance, allowing for efficient power conversion in organic PV cells under intense (>15 suns) AM1.5 illumination. This device structure demonstrates that control of exciton diffusion in solid-state organic devices leads to a significant increase in the photon-to-carrier conversion efficiency. ©2000 American Institute of Physics. Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes P Peumans V Bulovic SR Forrest doi:10.1063/1.126433 Applied Physics Letters, Vol. 76, No. 19. (2000), pp. 2650-2652. 2006-04-15T10:58:32-00:00 2000 Applied Physics Letters 76 19 2650 2652 AIP bcp cupc photovoltaic http://www.citeulike.org/user/dwinston/article/2937189 <i>Advanced Materials, Vol. 16, No. 3. (2004), pp. 226-231.</i><br /><br />No abstract. Highly Oriented and Ordered Arrays from Block Copolymers via Solvent Evaporation S H Kim M J Misner T Xu M Kimura T P Russell doi:10.1002/adma.200304906 Advanced Materials, Vol. 16, No. 3. (2004), pp. 226-231. 2008-06-27T13:33:04-00:00 2004 Advanced Materials 16 3 226 231 bcp solvent_annealing http://www.citeulike.org/user/dwinston/article/2937187 <i>J. Am. Chem. Soc., Vol. 128, No. 23. (14 June 2006), pp. 7622-7629.</i><br /><br />Abstract: The self-assembly of triblock copolymers of poly(ethylene oxide-b-methyl methacrylate-b-styrene) (PEO-b-PMMA-b-PS), where PS is the major component and PMMA and PEO are minor components, provides a robust route to highly ordered, nanoporous arrays with cylindrical pores of 10-15 nm that show promise in block copolymer lithography. These ABC triblock copolymers were synthesized by controlled living radical polymerization, and after solvent annealing, thin films showing defect-free cylindrical microdomains were obtained. The key to the successful generation of highly regular, porous thin films is the use of PMMA as a photodegradable mid-block which leads to nanoporous structures with an unprecedented degree of lateral order. The power of using a triblock copolymer when compared to a traditional diblock copolymer is evidenced by the ability to exploit and combine the advantages of two separate diblock copolymer systems, the high degree of lateral ordering inherent in PS-b-PEO diblocks plus the facile degradability of PS-b-PMMA diblock copolymer systems, while negating the corresponding disadvantages, poor degradability in PS-b-PEO systems and no long-range order for PS-b-PMMA diblocks. Defect-Free Nanoporous Thin Films from ABC Triblock Copolymers J Bang SH Kim E Drockenmuller MJ Misner TP Russell CJ Hawker doi:10.1021/ja0608141 J. Am. Chem. Soc., Vol. 128, No. 23. (14 June 2006), pp. 7622-7629. 2008-06-27T13:31:56-00:00 2006 J. Am. Chem. Soc. 128 23 7622 7629 bcp solvent_annealing http://www.citeulike.org/user/dwinston/article/2776716 <i>Journal of Applied Physics, Vol. 27, No. 8. (1956), pp. 900-904.</i><br /><br />View This Record in Scopus Two-Dimensional Motion of Idealized Grain Boundaries WW Mullins Journal of Applied Physics, Vol. 27, No. 8. (1956), pp. 900-904. 2008-05-09T21:44:58-00:00 1956 Journal of Applied Physics 27 8 900 904 AIP bcp http://www.citeulike.org/user/dwinston/article/2919153 <i>Science, Vol. 302, No. 5652. (12 December 2003), pp. 1904-1905.</i><br /><br />10.1126/science.1091064 CHEMISTRY: Polymers Get Organized David Bucknall Harry Anderson doi:10.1126/science.1091064 Science, Vol. 302, No. 5652. (12 December 2003), pp. 1904-1905. 2008-06-23T15:41:50-00:00 2003 Science 302 5652 1904 1905 bcp short http://www.citeulike.org/user/dwinston/article/2924946 <i>Nano Lett., Vol. 7, No. 9. (12 September 2007), pp. 2789-2794.</i><br /><br />Abstract: We report measurements of rapid ordering and preferential alignment in block copolymer films zone annealed below the order-disorder transition temperature. The orientational correlation lengths measured after approximately 5 h above the glass-transition temperature ( 2 m) were an order of magnitude greater than that obtained under equivalent static annealing. The ability to rapidly process polymers with inaccessible order-disorder transition temperatures suggests zone annealing as a route toward more robust nanomanufacturing methods based on block copolymer self-assembly. Orientational Order in Block Copolymer Films Zone Annealed below the Order-Disorder Transition Temperature BC Berry AW Bosse JF Douglas RL Jones A Karim doi:10.1021/nl071354s Nano Lett., Vol. 7, No. 9. (12 September 2007), pp. 2789-2794. 2008-06-25T03:19:02-00:00 2007 Nano Lett. 7 9 2789 2794 bcp http://www.citeulike.org/user/dwinston/article/2782248 <i>Annual Review of Materials Research, Vol. 31, No. 1. (2001), pp. 323-355.</i><br /><br />Abstract A two-part review of research concerning block copolymer thin films is presented. The first section summarizes experimental and theoretical studies of the fundamental physics of these systems, concentrating upon the forces that govern film morphology. The role of film thickness and surface energetics on the morphology of compositionally symmetric, amorphous diblock copolymer films is emphasized, including considerations of boundary condition symmetry, so-called hybrid structures, and surface chemical expression. Discussions of compositionally asymmetric systems and emerging research areas, e.g., liquid-crystalline and A-B-C triblock systems, are also included. In the second section, technological applications of block copolymer films, e.g., as lithographic masks and photonic materials, are considered. Particular attention is paid to means by which microphase domain order and orientation can be controlled, including exploitation of thickness and surface effects, the application of external fields, and the use of patterned substrates. BLOCK COPOLYMER THIN FILMS: Physics and Applications Michael Fasolka Anne Mayes doi:10.1146/annurev.matsci.31.1.323 Annual Review of Materials Research, Vol. 31, No. 1. (2001), pp. 323-355. 2008-05-10T02:02:55-00:00 2001 Annual Review of Materials Research 31 1 323 355 bcp self-assembly templated http://www.citeulike.org/user/dwinston/article/2937190 <i>Advanced Materials, Vol. 16, No. 23-24. (2004), pp. 2119-2123.</i><br /><br />No abstract. Solvent-Induced Ordering in Thin Film Diblock Copolymer/Homopolymer Mixtures S H Kim M J Misner T P Russell doi:10.1002/adma.200306577 Advanced Materials, Vol. 16, No. 23-24. (2004), pp. 2119-2123. 2008-06-27T13:33:29-00:00 2004 Advanced Materials 16 23-24 2119 2123 bcp solvent_annealing