Light-stress-induced pigment changes and evidence for anthocyanin photoprotection in apples

Fruit of two apple (Malus domestica Borkh.) cultivars, differing in their ability to produce anthocyanin pigments when exposed to sunlight, have been studied using reflectance spectroscopy. Comparison of the spectra shows that apple anthocyanins in vivo possess a symmetric absorption band at 500-600 nm with a maximum near 550 nm. Anthocyanins considerably increase light absorption by apples. In on-tree-ripening Zhigulevskoe apples, accumulating high amounts of anthocyanin pigments, chlorophyll contents in sunlit and shaded sides of the fruits are found to be similar. In contrast, frequently considerably lower chlorophyll content is estimated in sunlit compared with shaded sides of Antonovka apples exhibiting low potential for anthocyanin formation. Sunlight also brings about an increase of carotenoid content over that of chlorophylls and accumulation of substances responsible for light absorption in the range 350-400 nm. The rates of high-light-induced chlorophyll bleaching in red zones of fruit containing anthocyanins are considerably lower than those in green zones and decrease with an increase in the pigment content. Anthocyanins show more stability to irradiation than chlorophylls. A protective function of anthocyanins against both light-induced stress in, and damage to, apples is suggested. It is proposed that anthocyanins function as an effective internal light trap filling the chlorophyll absorption gap in the green-orange part of the visible spectrum.     

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …     

Nonlinear compression of optical solitons

In this paper, we consider nonlinear Schrödinger (NLS) equations, both in the anomalous and normal dispersive regimes, which govern the propagation of a single field in a fiber medium with phase modulation and fibre gain (or loss). The integrability conditions are arrived from linear eigen value problem. The variable transformations which connect the integrable form of modified NLS equations are presented. We succeed in Hirota bilinearzing the equations and on solving, exact bright and dark soliton solutions are obtained. From the results, we show that the soliton is alive, i.e. pulse area can be conserved by the inclusion of gain (or loss) and phase modulation effects.     

Dynamic and electrooptical properties of FH…F and FH…N hydrogen bridges

The dynamic and electrooptical parameters of the hydrogen bridges in (HF)₂, FH…FCD₃, FH…NCH, and FH…NCCH₃ complexes were calculated by the MINDO/3 method. Relationships between these parameters have been found. These parameters for the F−H…Y bridges mainly coincide with the relationships previously established for the hydrogen O−H…Y bridges. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1067–1069, May, 1997.     

Symplectic supercuspidal representations and related problems

In this paper, we summarize the basic structures and properties of irreducible symplectic supercuspidal representations of GLn(F) over a p-adic local field F with characteristic zero, and explore possible topics for further investigation.     

Optical properties and nondestructive estimation of anthocyanin content in plant leaves.

Absorption and reflectance spectra of maple (Acer platanoides), cotoneaster (Cotoneaster alaunica), dogwood (Cornus alba) and pelargonium (Pelargonium zonale) leaves with a wide range of pigment content and composition were studied in visible and near-infrared spectra in order to reveal specific anthocyanin (Anth) spectral features in leaves. Comparing absorption spectra of Anth-containing and Anth-free leaves with the same chlorophyll (Chl) content, absorption spectra of Anth in leaves were derived. The main spectral feature of Anth absorption in vivo was a peak around 550 nm; the peak magnitude was closely related to Anth content. A quantitative nondestructive technique was developed to subtract Chl contribution to reflectance in this spectral region and retrieve Anth content from reflectance over a wide range of pigment content and composition. Anth reflectance index in the form ARI = (R550)-1 - (R700)-1, where (R550)-1 and (R700)-1 are inverse reflectances at 550 and 700 nm, respectively, allowed an accurate estimation of Anth accumulation, even in minute amounts, in intact senescing and stressed leaves.     

Calculation of the diffusion coefficient in a liquid based on the force covariance function

Methods of optimal use of statistical information on the Brownian motion of molecules in a liquid for calculating the diffusion coefficient are considered. Relationships between covariance functions for the displacement of a molecule, its velocity, and the force acting on the molecule are established. It is proposed the method of calculation of the diffusion coefficient estimates should be made using the force covariance function, which enables to reduce the time of simulation of the molecular motion. The proposed method is used for callculating diffusion coefficients for some systems.     

Investigation into the nature of intermolecular and ion—molecular interactions in H-groups of hydroxyl-containing compounds and calculation of vibration frequencies for A-H and H⋯X bonds using the anharmonic approach

Quantum chemistry calculation methods are used to study the H-bond formation in ion—molecular and molecular complexes of hydroxyl-containing compounds. The effect of electrostatic fields of electron donors and acceptors on the H-bond stability and the frequency of OH valence vibrations is studied. Charge transfer effects are analyzed. Potential surface parameters for complexes are calculated and the results used to calculate vibration frequencies for fundamental transitions and the first overtones for valence A-H and H?X vibrations in multiatomic models using the anharmonic approximation.