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Regular Shape (regular + shape)
Selected AbstractsSelf-Assembled Organic,Inorganic Hybrid Elastic Crystal via Biomimetic MineralizationADVANCED MATERIALS, Issue 33 2010Halei Zhai Organic,inorganic hybrid rhombs with regular shape and a lamellar superstructure are biomimetically fabricated by the cooperative self-assembly of bovine serum albumin (BSA), sodium bis-2-ethylhexyl sulfosuccinate (AOT), and calcium phosphate (see figure). Although crystalline calcium phosphate is the main component, the hybrid crystals are elastic and they can be flexible under external stresses. [source] Effect of a crystallite size distribution on X-ray diffraction line profiles and whole-powder-pattern fittingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-2 2000J. I. Langford A distribution of crystallite size reduces the width of a powder diffraction line profile, relative to that for a single crystallite, and lengthens its tails. It is shown that estimates of size from the integral breadth or Fourier methods differ from the arithmetic mean of the distribution by an amount which depends on its dispersion. It is also shown that the form of `size' line profiles for a unimodal distribution is generally not Lorentzian. A powder pattern can be simulated for a given distribution of sizes, if it is assumed that on average the crystallites have a regular shape, and this can then be compared with experimental data to give refined parameters defining the distribution. Unlike `traditional' methods of line-profile analysis, this entirely physical approach can be applied to powder patterns with severe overlap of reflections, as is demonstrated by using data for nanocrystalline ceria. The procedure is compared with alternative powder-pattern fitting methods, by using pseudo-Voigt and Pearson VII functions to model individual line profiles, and with transmission electron microscopy (TEM) data. [source] Solid lipid nanoparticles (SLN) as carriers for the topical delivery of econazole nitrate: in-vitro characterization, ex-vivo and in-vivo studiesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2007Vanna Sanna Solid lipid nanoparticles (SLN) designed for topical administration of econazole nitrate (ECN), were prepared by o/w high-shear homogenization method using different ratios of lipid and drug (5:1 and 10:1). SLN were characterized in terms of particle size, morphology, encapsulation efficiency and crystalline structure. After incorporation of SLN into hydrogels, rheological measurements were performed, and ex-vivo drug permeation tests were carried out using porcine stratum corneum (SC). In-vivo study of percutaneous absorption of ECN as a function of application time and composition of gels was carried out by tape-stripping technique. Penetration tests of the drug from a conventional gel were performed as comparison. High-shear homogenization method resulted in a good technique for preparation of ECN-loaded SLN. Particles had a mean diameter of about 150 nm and a regular shape and smooth surface. The encapsulation efficiency values were about 100%. Ex-vivo tests showed that SLN were able to control the drug release through the SC; the release rate depended upon the lipid content on the nanoparticles. In-vivo studies demonstrated that SLN promoted a rapid penetration of ECN through the SC after 1 h and improved the diffusion of the drug in the deeper skin layers after 3 h of application compared with the reference gel. [source] Morphological characteristics of on-farm water storages and their similarity to natural water bodies in the Border Rivers Catchment, AustraliaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2010Susan Lutton Abstract 1.Natural wetlands throughout the world are under threat from water resource development required to support an ever increasing population. In the Border Rivers Catchment in Queensland, Australia, a large irrigation industry and highly variable flow regime have necessitated the building of large on-farm water storages. With the decline in number and size of natural wetlands, the presence of these storages on the floodplain has raised the question of their suitability as alternative habitat for aquatic fauna. This paper explores the variety of water storage types in the Border Rivers Catchment and how their morphology compares with that of natural wetlands , in particular, factors likely to influence aquatic biodiversity. 2.Storages and natural wetlands formed two distinct groups based on morphology. Storages tended to be large, deep structures with a more regular shape while natural wetlands were irregular and shallow with large perimeters. Although there was a degree of variability amongst the storage sites, a large proportion fell into one group and were considered ,typical storages'. Typical storages contained tailwater and had the following characteristics: situated 3,km from the source river, 10 years old, embankment height of 5,m, area of 400,000,m2, perimeter of 2.5,km and capacity of 1,700,000,m3. 3.Due to their uniform structure we believe that most on-farm storages are unlikely to support as diverse or abundant an aquatic population as natural wetlands. The presence of tailwater and associated chemicals is also likely to reduce the aquatic biodiversity of storages compared with natural wetlands. While they may be unsuitable as replacement wetlands, given their numbers they could provide significant aquatic habitat across the landscape, if managed effectively. Copyright © 2009 John Wiley & Sons, Ltd. [source] Purification, crystallization and preliminary X-ray analysis of an acetylxylan esterase from Bacillus pumilusACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2001Stefano Benini The gene encoding for acetylxylan esterase from Bacillus pumilus has been cloned and expressed in Escherichia coli. The recombinant protein has been purified to homogeneity and crystallized. The crystals obtained are of regular shape of dimensions 0.05 × 0.05 × 0.05,mm with R32 symmetry and diffract to 2.0,Å using synchrotron radiation. [source] Supercritical antisolvent micronisation of synthetic all- trans -,-carotene with tetrahydrofuran as solvent and carbon dioxide as antisolventJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2009Miguel A Tavares Cardoso Abstract BACKGROUND: Supercritical antisolvent (SAS) micronisation of synthetic trans -,-carotene was studied using tetrahydrofuran (THF) as solvent and supercritical carbon dioxide (CO2) as antisolvent, with the objective of increasing its bioavailability and facilitating its dispersion in oil and emulsion formulations as a result of its smaller particle size. The micronised powder was analysed by scanning electron microscopy and high-performance liquid chromatography. Micronisation experiments were performed in order to evaluate the effects of temperature (308.15,333.15 K), pressure (6.5,13 MPa) and concentration of the liquid solution (6,9 g L,1). The effect of the supercritical CO2/THF flow ratio in the range between 4 and 44 (on a mass basis) was also analysed. Determinations of equilibrium concentrations of ,-carotene in the CO2/THF mixture were also performed. RESULTS: The particle size obtained ranged from 1 to 500 µm, with mean particle diameters around 100 µm. Three types of morphology were found in the precipitated powder: crystalline with superficial pores and leaf-like appearance; crystalline with regular shapes and blade-like edges; and crystalline without superficial pores and leaf-like apearance. The Peng,Robinson equation of state was used to calculate the density of the CO2/THF binary mixture, and the solubility of ,-carotene in this mixture was correlated with its density. CONCLUSION: The use of the SAS technique to micronise ,-carotene proved to be efficient, and the absence of degradation in the micronised powder allows the industrial application of this technique. Copyright © 2008 Society of Chemical Industry [source] Ammonium oxotrifluorotitanate: morphology control and conversion to anatase TiO2PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008Lei Zhou Abstract Uniform ammonium oxotrifluorotitanate (NH4TiOF3) mesocrystals were synthesized from an aqueous solution containing (NH4)2TiF6 and H3BO3 in presence of nonionic surfactant. Effects of various reaction conditions on the morphology of the NH4TiOF3 mesocrystals were examined by electron microscopy techniques. Results indicate that static solution, high surfactant concentration and low reaction temperature enhance the formation of uniform NH4TiOF3 mesocrystals with regular shapes. By sintering in atmosphere, the NH4TiOF3 mesocrystals were converted to anatase TiO2, which retain the original shapes of the NH4TiOF3 precursor due to similarities on their atom structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||