Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Self Assembly of Honeycomb TiO2 Coatings by Tea-Leaf Extracts as the Dispersoids  [PDF]
Masayuki Kamei
World Journal of Condensed Matter Physics (WJCMP) , 2011, DOI: 10.4236/wjcmp.2011.13010
Abstract: Photo catalytic TiO2 coatings with well defined honeycomb structure were successfully self-assembled on glass substrates by a simple “dip and burn solgel method“. The crux of this new method is that the starting material for the sol-gel coating (the water solution of ammonium titanium citrate) was “doped” with “tea-leaf extracts”. Tea-leaf extracts were completely dissolved in the water solution of ammonium titanium citrate and nucleate uniformly during the drying procedure of the coating precursor formation. This uniformly dispersed nucleation of the “tea-leaf extracts (tannin, catechin…)” were extracted during calcinations and leaving honeycomb-cell like nano-structure in the TiO2 coatings. Self-assembled cells were uniformly distributed in the TiO2 coatings and the diameter of the cells was in the range of 200 - 1000 nm. Fine honeycomb structures were clearly observed with microscopic observations.
Optimized Interactions for Targeted Self-Assembly: Application to Honeycomb Lattice  [PDF]
Mikael Rechtsman,Frank Stillinger,Salvatore Torquato
Physics , 2005, DOI: 10.1103/PhysRevLett.95.228301
Abstract: We devise an inverse statistical-mechanical methodology to find optimized interaction potentials that lead spontaneously to a target many-particle configuration. Target structures can possess varying degrees of disorder, thus extending the traditional idea of self-assembly to incorporate both amorphous and crystalline structures as well as quasicrystals. For illustration purposes, our computational technique is applied to yield an optimized isotropic (non-directional) pair potential that spontaneously yields the three-coordinated honeycomb lattice as the ground state structure in two dimensions. This target choice is motivated by its three-dimensional analog, the diamond lattice, which is known to possess desirable photonic bandgap properties.
Rings sliding on a honeycomb network: Adsorption contours, interactions, and assembly of benzene on Cu(111)  [PDF]
K. Berland,T. L. Einstein,P. Hyldgaard
Physics , 2009, DOI: 10.1103/PhysRevB.80.155431
Abstract: Using a van der Waals density functional (vdW-DF) [Phys. Rev. Lett. 92, 246401 (2004)], we perform ab initio calculations for the adsorption energy of benzene (Bz) on Cu(111) as a function of lateral position and height. We find that the vdW-DF inclusion of nonlocal correlations (responsible for dispersive interactions) changes the relative stability of eight binding-position options and increases the binding energy by over an order of magnitude, achieving good agreement with experiment. The admolecules can move almost freely along a honeycomb web of "corridors" passing between fcc and hcp hollow sites via bridge sites. Our diffusion barriers (for dilute and two condensed adsorbate phases) are consistent with experimental observations. Further vdW-DF calculations suggest that the more compact (hexagonal) Bz-overlayer phase, with lattice constant a = 6.74 \AA, is due to direct Bz-Bz vdW attraction, which extends to ~8 \AA. We attribute the second, sparser hexagonal Bz phase, with a = 10.24 \AA, to indirect electronic interactions mediated by the metallic surface state on Cu(111). To support this claim, we use a formal Harris-functional approach to evaluate nonperturbationally the asymptotic form of this indirect interaction. Thus, we can account well for benzene self-organization on Cu(111).
Effect of TiO2 pigment gradation on the properties of thermal insulation coatings  [PDF]
Lu-wei Shen,Ya-mei Zhang,Pei-gen Zhang,Jin-jie Shi,Zheng-ming Sun
- , 2016, DOI: https://doi.org/10.1007/s12613-016-1371-4
Abstract: This study was designed to evaluate the thermal performance and mechanical properties of coatings with different gradations of TiO2 pigments. The solar reflectance, cooling performance, wash resistance, and film adhesion strength of the coatings were investigated. The influence of TiO2 powder gradation on the final properties of the coatings was studed. The solar reflectance and the thermal insulation were observed to increase with increasing content of nanosized TiO2. The mechanical properties of the coatings, such as their wash resistance and film adhesion strength, were observed to increase with increased incorporation of nanosized TiO2. Such improvements in the properties of the coatings were attributed to the greater specific surface area and lower thermal conductivity of nanosized TiO2 particles compared to normal TiO2 particles.
Honeycomb arrays  [PDF]
Simon R. Blackburn,Anastasia Panoui,Maura B. Paterson,Douglas R. Stinson
Mathematics , 2009,
Abstract: A honeycomb array is an analogue of a Costas array in the hexagonal grid; they were first studied by Golomb and Taylor in 1984. A recent result of Blackburn, Etzion, Martin and Paterson has shown that (in contrast to the situation for Costas arrays) there are only finitely many examples of honeycomb arrays, though their bound on the maximal size of a honeycomb array is too large to permit an exhaustive search over all possibilities. The present paper contains a theorem that significantly limits the number of possibilities for a honeycomb array (in particular, the theorem implies that the number of dots in a honeycomb array must be odd). Computer searches for honeycomb arrays are summarised, and two new examples of honeycomb arrays with 15 dots are given.
Influence of dispersoids on the creep behavior of dispersion strengthened aluminum materials  [cached]
Carre?o, F.,Ruano, O. A.
Revista de Metalurgia , 1997,
Abstract: The creep behavior of a rapidly solidified Al-6.5%Fe-0.6%V-1.3%Si dispersion strengthened material containing 16 volume % of dispersoids has been studied by means of tensile tests at high temperatures from 483 to 821 K. The imposed strain rates ranged from 2.5 10-6 to 10-2s-1. The microstructure was very fine, consisting of submicron grains and small hard round-shaped dispersoids of about 54 nm. The creep behavior was characterized by high apparent stress exponents and high activation energies that are not accurately predicted by models from the literature. Therefore, a creep equation is developed to describe the creep behavior of the studied aluminum dispersion strengthened material and other materials with similar microstructures. The proposed equation is a generalization of conventional slip creep equations without the use of a threshold stress. Se estudió el comportamiento en fluencia del material solidificado rápidamente Al-6,5%Fe-0,6%V-1,3%Si, reforzado por dispersión que contenía una fracción de volumen de dispersoides de 16 %, mediante ensayos de tracción a altas temperaturas desde 483 a 821 K. Las velocidades de deformación impuestas variaron desde 2,5 10-6 to 10-2s-1. La microestructura, que era muy fina, estaba formada por granos submicrométricos y peque os dispersoides redondeados y duros de unos 54 nm. El comportamiento en fluencia se caracterizó por altos exponentes de la tensión aparente y altas energías de activación aparentes que no se predicen con exactitud por modelos de la literatura. Por ello, se ha desarrollado una ecuación de fluencia que describe el comportamiento del material de base aluminio reforzado por dispersión y de otros materiales de microestructura similar. La ecuación propuesta es una generalización de ecuaciones de fluencia convencionales por movimiento de dislocaciones y no emplea una tensión umbral.
The Honeycomb Conjecture  [PDF]
Thomas C. Hales
Mathematics , 1999,
Abstract: The classical honeycomb conjecture asserts that any partition of the plane into regions of equal area has perimeter at least that of the regular hexagonal honeycomb tiling. Pappus discusses this problem in his preface to Book V. This paper gives the first general proof of the conjecture. The revision is the published version, which allows disconnected honeycomb cells and gaps between cells.
Immersed nano-sized Al dispersoids in an Al matrix; effects on the structural and mechanical properties by Molecular Dynamics simulations  [PDF]
H Chamati,M S Stoycheva,G A Evangelakis
Physics , 2003, DOI: 10.1088/0953-8984/16/28/021
Abstract: We used molecular dynamics simulations based on a potential model in analogy to the Tight Binding scheme in the Second Moment Approximation to simulate the effects of aluminum icosahedral grains (dispersoids) on the structure and the mechanical properties of an aluminum matrix. First we validated our model by calculating several thermodynamic properties referring to the bulk Al case and we found good agreement with available experimental and theoretical data. Afterwards, we simulated Al systems containing Al clusters of various sizes. We found that the structure of the Al matrix is affected by the presence of the dispersoids resulting in well ordered domains of different symmetries that were identified using suitable Voronoi analysis. In addition, we found that the increase of the grain size has negative effect on the mechanical properties of the nanocomposite as manifested by the lowering of the calculated bulk moduli. The obtained results are in line with available experimental data.
Ecophysiology of tea
De Costa, W.A. Janendra M.;Mohotti, A. Janaki;Wijeratne, Madawala A.;
Brazilian Journal of Plant Physiology , 2007, DOI: 10.1590/S1677-04202007000400005
Abstract: tea [camellia sinensis (l.) o. kuntze] is one of the most important beverage crops in the world. the major tea-growing regions of the world are south-east asia and eastern africa where it is grown across a wide range of altitudes up to 2200 m a.s.l.. this paper reviews the key physiological processes responsible for yield determination of tea and discusses how these processes are influenced by genotypic and environmental factors. yield formation of tea is discussed in terms of assimilate supply through photosynthesis and formation of harvestable sinks (i.e. shoots). the photosynthetic apparatus and partial processes (i.e. light capture, electron transport and carboxylation) of tea show specific adaptations to shade. consequently, maximum light-saturated photosynthetic rates of tea are below the average for c3 plants and photoinhibition occurs at high light intensities. these processes restrict the source capacity of tea. tea yields are sink-limited as well because shoots are harvested before their maximum biomass is reached in order to maintain quality characters of made tea. in the absence of water deficits, rates of shoot initiation and extension are determined by air temperature and saturation vapour pressure deficit, with the former having positive and the latter having negative relationships with the above rates. during dry periods, when the soil water deficit exceeds a genotypically- and environmentally-determined threshold, rates of shoot initiation and extension are reduced with decreasing shoot water potential. tea yields respond significantly to irrigation, a promising option to increase productivity during dry periods, which are experienced in many tea-growing regions.

金属学报(英文版) , 2005,
Abstract: A novel TiO2-ZnFe2O4 coating is prepared by plasma spraying. The effects of spra ying parameters and the composition of powders on the microstructure, surface mo rphology and photo-absorption of plasma sprayed coatings are studied. The photoc atalytic efficiency of the as-sprayed coatings is evaluated through the photo mi neralization of methylene blue. It was found that TiO2 coatings can decompose me thylene blue under the illumination of ultraviolet rays, and the degrading effic iency is improved with an increase in the content of FeTiO3 in the coatings. How ever, the presence of large amount of ZnFe2O4 compound will substantially lower the photocatalytic efficiency of the TiO2-ZnFe2O4 coatings for the unfavorable p hoto-excited electron-hole transfer process.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.