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The reaction between nitric oxide (•NO) and oxygen yields reactive species capable of oxidizing and nitrosating proteins, as well as deaminating DNA bases. Although this reaction is considered too slow to be biologically relevant, it has been shown that membranes, lipoproteins, mitochondria and possibly proteins can accelerate this reaction. This effect stems from the higher solubility of both •NO and O2in the hydrophobic phase of these biological particles, leading to a concentration of both reagents and so a higher rate of reaction. It has been determined that this reaction occurs from 30 to 300 times more rapidly within the membrane, while even higher values have been suggested for proteins. The autoxidation of •NO in membranes is not the main route for cellular •NO consumption but an important consequence of this phenomenon is to focus the generation of significant amounts of oxidizing and nitrosating molecules (nitrogen dioxide and dinitrogen trioxide) in the small volume comprised by cellular membranes. Even so, these reactive species are diffusible and their ultimate fate will depend on the reactivity towards available substrates rather than on physical barriers. The acceleration of •NO autoxidation by biological hydrophobic phases may thus be a general phenomenon that increases in importance in cases of •NO overproduction. IUBMB Life, 59: 243-248, 2007 [ABSTRACT FROM AUTHOR]

The electromagnetic-transmission properties of opal-like structures made of glass marbles has been measured. All the cases show strongly rejected bands at frequencies corresponding to a Bragg 2nd-order of diffraction. The results show good agreement with appropriate simulations. Moreover, the structure presents a lens effect when placed properly at the output of a conventional horn antenna. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 472–475, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21204 [ABSTRACT FROM AUTHOR]

Chloroplasts redistribute and/or reorientate in the cell as a response to the light direction, resulting in patterns typical for light of low or high fluence rate, respectively. Usually, the main photoreceptor pigment is a blue-UV-absorbing pigment ('cryptochrome'), but in a few exceptional cases, the reversible red/far-red system phytochrome is involved. Detection of light direction is based on light refraction and/or on dichroic orientation of photoreceptor molecules. Membrane effects, intracellular calcium redistribution and calcium-calmodulin inter-action are discussed as likely steps in signal transduction. In the response mechanism the actin-myosin system is involved. However, several details of perception, transduction and response are still unsolved and open for discussion. Particularly interesting are the cases of multiple photoreceptor systems, i.e. those where separate transduction chains are started which coact or interact with each other. This raises the question as to the evolution of multiple photoreceptor systems under the assumption that light-oriented chloroplast movements serve to optimize photosynthesis. [ABSTRACT FROM AUTHOR]

Artists do not always pursue photographic realism. The image abstraction and deformation of three-dimensional scenes are methods to communicate ideas. Images are the visual interpretation of real life or imaginary scenes. This paper describes the idea of an infinite reflection model in which synthetic objects to be rendered are surrounded by closed reflective surfaces. The closed mirror surfaces create the 'feedback' effect which deforms objects inside the reflective space. Lens distortion effects are achieved by surrounding infinitely reflective curved surfaces. This technique provides a new visual tool for artists and graphic designers. [ABSTRACT FROM AUTHOR]