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Hexagonal Array (hexagonal + array)
Selected AbstractsHighly Ordered Hexagonal Arrays of Hybridized Micelles from Bimodal Self-Assemblies of Diblock Copolymer MicellesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2010Seong Il Yoo Abstract We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene,poly(4-vinyl pyridine), PS,PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS,PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS,PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles. In addition, the hybridized micelles arranged themselves in a highly ordered hexagonal array, the diameter and center-to-center distance of which were precisely adjusted by varying the mixing ratio of small to large micelles in the bimodal assemblies. [source] Metallic nanoparticle array on GaN by microsphere lithographyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Giuseppe Y. Mak Abstract The optical characteristics of GaN blue-light (peak wavelength at 440 nm) light-emitting diode (LED) under the effect of localized surface plasmon (LSP) have been studied. Hexagonal arrays of triangular metallic nanoparticles deposited through a self-assembled silica microsphere mask have been fabricated using vertical deposition. By comparing the PL spectra of samples coated with Au, Al and Ag nanoparticles, it is found that Ag nanoparticles offer the most pronounced PL enhancement. The resonance wavelength was determined from optical transmission and verified by theoretical calculations. These results provide a cost-effective solution for improving the efficiency of LEDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A micropillar-integrated smart microfluidic device for specific capture and sorting of cellsELECTROPHORESIS, Issue 24 2007Yan-Jun Liu Abstract An integrated smart microfluidic device consisting of nickel micropillars, microvalves, and microchannels was developed for specific capture and sorting of cells. A regular hexagonal array of nickel micropillars was integrated on the bottom of a microchannel by standard photolithography, which can generate strong induced magnetic field gradients under an external magnetic field to efficiently trap superparamagnetic beads (SPMBs) in a flowing stream, forming a bed with sufficient magnetic beads as a capture zone. Fluids could be manipulated by programmed controlling the integrated air-pressure-actuated microvalves, based on which in situ bio-functionalization of SPMBs trapped in the capture zone was realized by covalent attachment of specific proteins directly to their surface on the integrated microfluidic device. In this case, only small volumes of protein solutions (62.5,nL in the capture zone; 375,nL in total volume needed to fill the device from inlet A to the intersection of outlet channels F and G) can meet the need for protein! The newly designed microfluidic device reduced greatly chemical and biological reagent consumption and simplified drastically tedious manual handling. Based on the specific interaction between wheat germ agglutinin (WGA) and N -acetylglucosamine on the cell membrane, A549 cancer cells were effectively captured and sorted on the microfluidic device. Capture efficiency ranged from 62 to 74%. The integrated microfluidic device provides a reliable technique for cell sorting. [source] Simple circuit to improve electric field homogeneity in contour-clamped homogeneous electric field chambersELECTROPHORESIS, Issue 7-8 2003José A. Herrera Abstract We redesigned contour-clamped homogeneous electric field (CHEF) circuitry to eliminate crossover distortion, to set identical potentials at electrodes of each equipotential pair and to drive pairs with transistors in emitter follower stages. An equipotential pair comprised the two electrodes set at the same potential to provide electric field homogeneity inside of the hexagonal array. The new circuitry consisted of two identical circuits, each having a resistor ladder, diodes and transistors. Both circuits were interconnected by diodes that controlled the current flow to electrodes when the array was energized in the ,A' or ,B' direction of the electric field. The total number of transistors was two-thirds of the total number of electrodes. Average voltage deviation from potentials expected at electrodes to achieve a homogeneous electric field was 0.06 V, whereas 0.44 V was obtained with another circuit that used transistors in push-pull stages. The new voltage clamp unit is cheap, generated homogeneous electric field, and gave reproducible and undistorted DNA band patterns. [source] Synthesis and Microstructural Characterisation of Two New One-Dimensional Members of the (A3NiMnO6),(A3Mn3O9), Homologous Series (A = Ba, Sr)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003María Hernando Abstract Two new members of the one-dimensional (A3NiMnO6),(A3Mn3O9), homologous series, with the compositions (Sr0.75Ba0.25)5NiMn3O12 and Sr9Ni2Mn5O21, have been synthesised. Their structures can each be described as a hexagonal array of infinite one-dimensional chains of face-sharing polyhedra, running parallel to the c axis and separated by the Sr/Ba cations. The structure of (Sr0.75Ba0.25)5NiMn3O12, which constitutes the (, = 3, , = 2) member of the series, is made up of three face-sharing octahedra linked by one trigonal prism. For Sr9Ni2Mn5O21 (, = 2, , = 1) the sequence of polyhedra along the chains corresponds to a motif consisting of two octahedra,one trigonal prism,three octahedra,one trigonal prism. The manganese atoms occupy the octahedral sites in both phases, while the Ni2+ cations are distributed in the trigonal-prismatic sites in a disordered way. Only a small fraction of these (close to 20%) is located at the centres of the trigonal prisms, 80% being displaced towards the rectangular faces of the polyhedra and giving rise to a square-planar-like coordination. Both oxides present twinned microstructures, as evidenced by SAED and HREM. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A metric for spaceHIPPOCAMPUS, Issue 12 2008Edvard I. Moser Abstract Not all areas of neuronal systems investigation have matured to the stage where computation can be understood at the microcircuit level. In mammals, insights into cortical circuit functions have been obtained for the early stages of sensory systems, where signals can be followed through networks of increasing complexity from the receptors to the primary sensory cortices. These studies have suggested how neurons and neuronal networks extract features from the external world, but how the brain generates its own codes, in the higher-order nonsensory parts of the cortex, has remained deeply mysterious. In this terra incognita, a path was opened by the discovery of grid cells, place-modulated entorhinal neurons whose firing locations define a periodic triangular or hexagonal array covering the entirety of the animal's available environment. This array of firing is maintained in spite of ongoing changes in the animal's speed and direction, suggesting that grid cells are part of the brain's metric for representation of space. Because the crystal-like structure of the firing fields is created within the nervous system itself, grid cells may provide scientists with direct access to some of the most basic operational principles of cortical circuits. © 2008 Wiley-Liss, Inc. [source] Formation of Lipid Emulsions and Clear Gels by Liquid Crystal EmulsificationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2007T. Suzuki Recently developed emulsion technologies for the formation of fine emulsions, lipid emulsions and clear gels by liquid crystal emulsification were reviewed. As a basic information on liquid crystal emulsification, the structures and characteristic behaviours of lyotropic liquid crystals were summarized. Formation of a liquid crystalline phase was often seen in emulsions and biological systems. The significance of liquid crystal formation during emulsification was analysed by comparing the states and stabilities of emulsions prepared by different processes. Then uses of liquid crystals for formation of the characteristic emulsions and gels were also discussed. In liquid crystal emulsification, an oil phase is dispersed directly into the lamellar liquid-crystalline phase composed of surfactant, glycerol and water to prepare a gel-like oil-in-liquid crystal emulsion. This is followed by dilution with the remaining water to produce an emulsion. From the phase behaviour during emulsification and analysis of the local motion of the liquid crystal membrane by fluorometry, it was confirmed that the interaction between surfactant and a polyol molecule such as glycerol promotes hydrogen bonding and enhances the strength of the lamellar liquid crystal membranes, which results in the formation of oil-in-liquid crystal emulsions. The interaction between the liquid crystal and oil was analysed from the changes in molecular motion of the membrane at the oil-liquid crystal interface using the spin label technique of electron spin resonance (ESR). The fluidity of the liquid crystal membrane did not change when oil was added, and therefore oil-in-liquid crystal emulsions of various oils were prepared by the identical process. This lack of dependence of the liquid crystal membrane on oil results in the unique properties of liquid crystal emulsification, which can be used for oils of various polarity and different molecular constituents. When a self-organizing artificial stratum corneum lipid containing pseudo-ceramide was used as a principal component of the oil, a multilamellar emulsion of concentric lamellar structure was formed. The multilamellar emulsion supplements the physiological function of stratum corneum by the identical mechanism as natural intercellular lipids. High-pressure treatment of the lipid emulsion produced a gel-like emulsion crystal, in which the homogeneous nanoemulsion droplets were arranged in a hexagonal array. This review paper was presented at the Conference of the Asian Societies of Cosmetic Scientists 2005 in Bangkok. [source] Formation of honeycomb-structured, porous films via breath figures with different polymer architecturesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2006Martina H. Stenzel Abstract Honeycomb-structured, porous films with pore sizes ranging from 200 nm to 7 ,m were prepared with breath figures. The regularity of the hexagonal array and the pore size was influenced by the polymer architecture and the casting conditions. A nanoscaled suborder next to the microarray was obtained with amphiphilic block copolymers. These films were shown to be suitable as surfaces for cell growth. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2363,2375, 2006 [source] Highly Ordered Hexagonal Arrays of Hybridized Micelles from Bimodal Self-Assemblies of Diblock Copolymer MicellesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2010Seong Il Yoo Abstract We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene,poly(4-vinyl pyridine), PS,PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS,PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS,PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles. In addition, the hybridized micelles arranged themselves in a highly ordered hexagonal array, the diameter and center-to-center distance of which were precisely adjusted by varying the mixing ratio of small to large micelles in the bimodal assemblies. [source] Integration of Density Multiplication in the Formation of Device-Oriented Structures by Directed Assembly of Block Copolymer,Homopolymer BlendsADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Guoliang Liu Abstract Non-regular, device-oriented structures can be directed to assemble on chemically nanopatterned surfaces such that the density of features in the assembled pattern is multiplied by a factor of two or more compared to the chemical pattern. By blending the block copolymers with homopolymers and designing the chemical pattern rationally, complicated structures such as bends, jogs, junctions, terminations, and combined structures are fabricated. Previously, directed assembly of block copolymers has been shown to enhance the resolution of lithographic processes for hexagonal arrays of spots and parallel lines, corresponding to the bulk morphologies of block copolymer systems, but this is the first demonstration of enhanced resolution for more complicated, device-oriented features. This fundamental knowledge broadens the range of technologies that can be served by the directed assembly of block copolymers. [source] Electrochemical Synthesis of CdSe Quantum-Dot Arrays on a Graphene Basal Plane Using Mesoporous Silica Thin-Film TemplatesADVANCED MATERIALS, Issue 4 2010Yong-Tae Kim A mesoporous silica film acts as a template and a potential equalizer between the edge/defect sites and the basal plane of a graphene sheet. Using an electrochemical deposition method of CdSe on these graphene sheets covered with a silica film results in CdSe quantum dots that are evenly distributed in regular hexagonal arrays (see figure). [source] Highly Ordered Hexagonal Arrays of Hybridized Micelles from Bimodal Self-Assemblies of Diblock Copolymer MicellesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 7 2010Seong Il Yoo Abstract We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene,poly(4-vinyl pyridine), PS,PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS,PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS,PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles. In addition, the hybridized micelles arranged themselves in a highly ordered hexagonal array, the diameter and center-to-center distance of which were precisely adjusted by varying the mixing ratio of small to large micelles in the bimodal assemblies. [source] Supramolecular Circular Helicates Formed by Destabilisation of Supramolecular DimersCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007Jacqueline Hamblin Dr. Abstract The effect of changes in the angles at the connection points of linear/circular helicates is explored as a route to control the nuclearity and architecture of metallo-supramolecular arrays. This effect is probed by changing the geometry of the metal centre used to assemble bis-pyridylimine ligands that contain a 1,3-bis(aminomethyl) benzene spacer group. Tetrahedral metal ions favour linear dimers, whereas octahedral nickel(II) predominantly gives a triangular circular helicate. Five-coordinate copper(II) falls in the middle of these extremes and results in the formation of solvent-dependent mixtures of dimer and trimer. The trinuclear, triangular, circular helicate structures, which result from coordination to copper(II) and nickel(II), are structurally characterised by X-ray crystallography and reveal that the units can aggregate into hexagonal arrays that contain anion-filled tube-like channels in the solid state. [source] | ||||||||||||||||||||||||||||