20 research outputs found
Radiation chemistry of solid-state carbohydrates using EMR
We review our research of the past decade towards identification of radiation-induced radicals in solid state sugars and sugar phosphates. Detailed models of the radical structures are obtained by combining EPR and ENDOR experiments with DFT calculations of g and proton HF tensors, with agreement in their anisotropy serving as most important criterion. Symmetry-related and Schonland ambiguities, which may hamper such identification, are reviewed. Thermally induced transformations of initial radiation damage into more stable radicals can also be monitored in the EPR (and ENDOR) experiments and in principle provide information on stable radical formation mechanisms. Thermal annealing experi-ments reveal, however, that radical recombination and/or diamagnetic radiation damage is also quite important. Analysis strategies are illustrated with research on sucrose. Results on dipotassium glucose-1-phosphate and trehalose dihydrate, fructose and sorbose are also briefly discussed. Our study demonstrates that radiation damage is strongly regio-selective and that certain general principles govern the stable radical formation
Au sujet de l'hamiltonien de spin applicable à un monocristal appartenant au système orthorhombique
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La résonance paramagnétique électronique d'un monocristal de glycocolle irradié par des rayons gamma
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Sur l'origine d'un déplacement radiatif observé en modulation spatiotemporelle des jets moléculaires
Au voisinage d'une résonance d'un jet moléculaire, le spectre de modulation produit par une cellule d'irradiation ayant une structure spatiale périodique, montre des composantes subissant un déplacement de type Bloch-Siegert et un autre déplacement lié au temps d'interaction et qui résulte des interférences des probabilités de transition dues aux deux composantes résonnante et antirésonnante du champ d'irradiation
Sur l'origine d'un déplacement radiatif observé en modulation spatiotemporelle des jets moléculaires
When a modular beam is irradiated near the molecular resonance by an irradiation cell having a periodic structure, one observes a spectrum, the components of which can have a displacement of the Bloch-Siegert type and a displacement bound to the interaction time. We propose an analysis of the second one which we explain by interferences of transition probabilities.Au voisinage d'une résonance d'un jet moléculaire, le spectre de modulation produit par une cellule d'irradiation ayant une structure spatiale périodique, montre des composantes subissant un déplacement de type Bloch-Siegert et un autre déplacement lié au temps d'interaction et qui résulte des interférences des probabilités de transition dues aux deux composantes résonnante et antirésonnante du champ d'irradiation
N-acyldopamines control striatal input terminals via novel ligand-gated cation channels
http://www.sciencedirect.com/science/article/B6T0C-4V3HHM3-1/2/22d594101b6927eca47e1b39b53ffce
Effect of short-term cadmium stress on Populus nigra L. detached leaves
Pollution by toxic metals, accumulating into soils as result of human activities, is a worldwide major concern in industrial countries. Plants exhibit different degrees of tolerance to heavy metals, as a consequence of their ability to exclude or accumulate them in particular tissues, organs or sub-cellular compartments. Molecular information about cellular processes affected by heavy metals is still largely incomplete. As a fast-growing, highly tolerant perennial plant species, poplar has become a model for environmental stress response investigations. To study the short-term effects of cadmium accumulation in leaves, we analyzed photosystem II (PSII) quantum yield, hydrogen peroxide (H2O2) generation, hormone levels variation, as well as proteome profile alteration of 50μM CdSO4 vacuum-infiltrated poplar (Populus nigra L.) detached leaves. Cadmium management brought about an early and sustained production of hydrogen peroxide, an increase of abscisic acid, ethylene and gibberellins content, as well as a decrease in cytokinins and auxin levels, whereas photosynthetic electron transport was unaffected. Proteomic analysis revealed that twenty-one proteins were differentially induced in cadmium-treated leaves. Identification of fifteen polypeptides allowed to ascertain that most of them were involved in stress response while the remaining ones were involved in photosynthetic carbon metabolism and energy production