Influence of salicylic acid on phytochelatin synthesis in Zea mays during Cd stress

Abstract: Presoaking maize (Zea mays) seeds in salicylic acid (SA) reduces damage caused by cadmium. In the present work the possible role of phytochelatins (PCs) in SA-mediated protection against Cd toxicity was investigated. Seeds were presoaked in 0.5 mM SA, and seedlings were grown in hydroponic solution containing 0, 0.01, 0.015, or 0.025 mM Cd. Treatment with Cd increased the PC levels in maize roots, but only slight changes were observed in the leaves. Long-term exposure to Cd decreased the phytochelatin synthase (PCS) activity in the roots and led to an increase in PCS and glutathione reductase (GR) activities in maize leaves. Although presoaking seeds in SA solution before exposure to Cd may reduce the level of heavy metal injury and has an effect on the composition of individual PCs, this protection is not directly connected with the altered regulation of PCs

Factors, affecting the formation of a modern teenager’s value system

The article examines some specific aspects of digestion by teenagers of social norms, values, behaviour samples, peculiar to modern society. The description of the value system of the Suvorov Military School and a secondary school students is given. The factors, affecting the formation of a teenager’s value system, such as family and social environment are discussed.Рассматриваются особенности усвоения подростками социальных норм, ценностей, образцов поведения, характерных для современного общества. Дается характеристика системы ценностных ориентаций обучающихся суворовского военного училища и средней общеобразовательной школы. Анализируются факторы, влияющие на формирование ценностных ориентаций подростка, такие как семья и социальное окружение

Optical spectra, crystal-field parameters, and magnetic susceptibility of the new multiferroic NdFe3(BO3)4

We report high-resolution optical absorption spectra for NdFe3(BO3)4 trigonal single crystal which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN = 33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g-factors. In particular, the values g(perpendicular) = 2.385, g(parallel) = 1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc=7.88 T and |JFN|= 0.48 K for the values of the local effective magnetic field at liquid helium temperatures at the Nd3+ site and the Nd - Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check reliability of our set of crystal field parameters we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn = -6.25 K (intra-chain interactions) and Jnnn = -1.92 K (inter-chain interactions) obtained from fitting agree well with the experimental data.Comment: 13 pages, 8 figures, 2 table

Infrared study of spin-Peierls compound alpha'-NaV2O5

Infrared reflectance of alpha'-NaV2O5 single crystals in the frequency range from 50 cm-1 to 10000 cm-1 was studied for a, b and c-polarisations. In addition to phonon modes identification, for the a-polarised spectrum a broad continuum absorption in the range of 1D magnetic excitation energies was found. The strong near-IR absorption band at 0.8 eV shows a strong anisotropy with vanishing intensity in c-polarisation. Activation of new phonons due to the lattice dimerisation were detected below 35K as well as pretransitional structural fluctuations up to 65K.Comment: 3 pages, 2 figures, 1 table. Contributed paper for the SCES'98 (15-18 July 1998, Paris). To be published in Physica

Folded modes in the infrared spectra of the spin-Peierls phase of CuGeO_3

Polarized far-infrared transmittance spectra of CuGeO_3 single crystals were measured at different temperatures (6K < T < 300K). Two spectral lines, at 284.2 cm-1 in E||c polarization and at 311.7 cm-1 in E||b polarization, appear at the temperature of the spin-Peierls transition and grow in intensity with decreasing temperature. Both of them are, most probably, folded modes of the dimerized lattice. We discuss a possible role of the spin-phonon interaction in the formation of the 311.7 cm-1 feature.Comment: 4 pages, 5 figures, 1 table; Submitted to Phys.Rev.B Second revision. Figures and text were slightly change