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Hydrophobic Layer (hydrophobic + layer)
Selected AbstractsEMBRYO YELLOW gene, encoding a subunit of the conserved oligomeric Golgi complex, is required for appropriate cell expansion and meristem organization in Arabidopsis thalianaGENES TO CELLS, Issue 6 2008Takaaki Ishikawa We identified an embryo yellow (eye) mutation in Arabidopsis that leads to the abnormal coloration and morphology of embryos. The eye mutant formed bushy plants, with aberrant organization of the shoot apical meristem (SAM) and unexpanded leaves with irregular phyllotaxy. The epidermal cells of the eye mutant were much smaller than that of the wild-type. Thus, EYE is required for expansion of cells and organs, and for formation of the organized SAM. Hydrophobic layers of epidermal cells were also disrupted, suggesting that EYE might be involved in the generation of the extra-cellular matrix. The mutated gene encoded a protein that is homologous to Cog7, a subunit of the conserved oligomeric Golgi (COG) complex, which is required for the normal morphology and function of the Golgi appratus. The eye mutation caused mislocalization of a Golgi protein. In addition, the size of the Golgi apparatus was also altered. Thus, EYE might be involved in transport or retention of Golgi-localized proteins and in maintenance of Golgi morphology. We propose that some Golgi-localized proteins, distributions of which are controlled by EYE, play important roles in expansion of cells and organs, and in formation of the properly organized SAM in plants. [source] Pseudobilayer Vesicle Formation via Layer-by-Layer Assembly of Hydrophobically Modified Polymers on Sacrificial Substrates,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2005J. Khopade Abstract A bilayer of a hydrophobically modified polyelectrolyte, octadecyl poly(acrylamide) (PAAm), sandwiched between the layers of a hydrophilic polyelectrolyte, poly(ethyleneimine) (PEI), is prepared by the sequential electrostatic,hydrophobic,electrostatic-interaction-driven self-assembly on planar and colloid substrates. This process results in a PEI/[PAAm]2/PEI-multilayer-coated substrate. The removal of a PAA/PEI/[PAAm]2/PEI-multilayer-coated decomposable colloidal template produces hollow capsules. Irregular hydrophobic domains of the [PAAm]2 bilayer in the PEI/[PAAm]2/PEI-multilayer capsule are infiltrated with a lipid to obtain a uniform, distinct hydrophobic layer, imparting the capsule with a pseudobilayer vesicle structure. [source] Implications of ideas on super-hydrophobicity for water repellent soilHYDROLOGICAL PROCESSES, Issue 17 2007G. McHale Abstract Water repellence is an important factor in soil erosion due to its role in inhibiting the re-establishment of vegetation after fire and due to its enhancement of run-off. Water repellence is studied across a range of diverse disciplines, such as chemistry, materials, textiles and soil and reclamation science. In recent years many basic studies of water repellence of materials have focused on the role of the sub-mm surface topography of a material in modifying the intrinsic hydrophobicity imparted by the surface chemistry to create super-hydrophobicity. In this report, we first illustrate the types of hydrophobic effects created by a suitable coupling of small scale surface topography with surface chemistry using three materials: an etched metal, a foam and a micro-fabricated pillar structure. These experiments demonstrate the general applicability of the ideas and suggest that they could apply to a granular material such as, a fine sandy soil, particularly when the grains have become coated with a hydrophobic layer. This applicability is confirmed by contact angle measurements of droplets of water on hydrophobic sand. A theoretical model describing the application of these ideas in a loose-packed, but regular, array of uniform spherical grains is then presented and discussed. When the grains are in a dry state initially, the effect of the surface is to increase the apparent water repellence as observed through the contact angle. However, when the spaces between the grains are filled with water, the effect is to provide greater wetting. To qualitatively confirm the enhancement of contact angle caused by the granular structure, model surfaces using 600 and 250 µm hydrophobic glass beads were created. On these surfaces, the contact angle of droplets of water was increased from 108° to 126° and 140° , respectively. Copyright © 2007 John Wiley & Sons, Ltd. [source] Tailoring surface properties of cellulose acetate membranes by low-pressure plasma processingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Chun Huang Abstract The aim of this study was to tailor the surface properties of cellulose acetate membranes using low-pressure plasma processing. Argon (Ar) plasma and Difluoromethane (CH2F2) plasma were used to control the surface wettabilities of cellulose acetate membranes. Optical emission spectroscopy was used to examine the various chemical species of low-pressure plasma processing. In this investigation, the plasma-treated surfaces were analyzed by X-ray photoelectron spectroscopy, while changes in morphology and surface roughness were determined with confocal laser scanning microscopy. Ar plasma activation resulted in hydrophilic surface. CH2F2 plasma deposited hydrophobic layer onto the cellulose acetate membrane because of strong fluorination of the top layer. The results reveal low-pressure plasma processing is an effective method to control the surface properties of cellulose acetate membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Wettablity of Poly(ethylene terephthalate) Substrates Modified by a Two-Step Plasma Process: Ultra Water Repellent Surface FabricationCHEMICAL VAPOR DEPOSITION, Issue 6 2004K. Teshima The fabrication of ultra-water-repellent poly(ethylene terephthalate) substrates has been achieved by a two-step plasma process. First, appropriate nanotextures are prepared on the substrate through an oxygen plasma treatment, and then a hydrophobic layer is coated on the nanotextured surfaces with plasma-enhanced CVD using tetramethylsilane. The resulting modified substrates show ultra-water-repellent characteristics with a water contact angle greater than 150° (Figure). [source] l -2-Aminobutyric acid: two fully ordered polymorphs with Z, = 4ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010Carl Henrik Görbitz The crystal structure of l -2-aminobutyric acid, an l -alanine analogue with an ethyl rather than a methyl side chain, has proved elusive owing to problems growing diffraction quality crystals. Good diffraction data have now been obtained for two polymorphs, in space groups P21 and I2, revealing surprisingly complex, yet fully ordered crystalline arrangements with Z, = 4. The closely related structures are divided into hydrophilic and hydrophobic layers, the latter being the thinnest ever found for an amino acid (other than ,-glycine). The hydrophobic layers furthermore contain conspicuous pseudo-centers-of-symmetry, leading to overall centrosymmetric intensity statistics. Uniquely, the four molecules in the asymmetric unit can be divided into two pairs that each forms an independent hydrogen-bond network. [source] Lamotrigine, an antiepileptic drug, and its chloride and nitrate saltsACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Balasubramanian Sridhar In lamotrigine [systematic name: 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine], C9H7Cl2N5, (I), the asymmetric unit contains one lamotrigine base molecule. In lamotriginium chloride [systematic name: 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium chloride], C9H8Cl2N5+·Cl,, (II), the asymmetric unit contains one lamotriginium cation and one chloride anion, while in lamotriginium nitrate, C9H8Cl2N5+·NO3,, (III), the asymmetric unit contains two crystallographically independent lamotriginium cations and two nitrate anions. In all three structures, N,H...N hydrogen bonds form an R22(8) dimer. In (I) and (II), hydrophilic layers are sandwiched between hydrophobic layers in the crystal packing. In all three structures, hydrogen bonds lead to the formation of a supramolecular hydrogen-bonded network. The significance of this study lies in its illustration of the differences between the supramolecular aggregation in the lamotrigine base and in its chloride and nitrate salts. [source] | |||||||||||||