Crystallite size distribution and dislocation structure determined by diffraction profile analysis: principles and practical application to cubic and hexagonal crystals

Two different methods of diffraction profile analysis are presented. In the first, the breadths and the first few Fourier coefficients of diffraction profiles are analysed by modified Williamson-Hall and Warren-Averbach procedures. A simple and pragmatic method is suggested to determine the crystallite size distribution in the presence of strain. In the second, the Fourier coefficients of the measured physical profiles are fitted by Fourier coefficients of well established ab initio functions of size and strain profiles. In both procedures, strain anisotropy is rationalized by the dislocation model of the mean square strain. The procedures are applied and tested on a nanocrystalline powder of silicon nitride and a severely plastically deformed bulk copper specimen. The X-ray crystallite size distributions are compared with size distributions obtained from transmission electron microscopy (TEM) micrographs. There is good agreement between X-ray and TEM data for nanocrystalline loose powders. In bulk materials, a deeper insight into the microstructure is needed to correlate the X-ray and TEM results

Az etilén státusz szerepe a paradicsom sóstressz akklimatizációjában

The gaseous plant hormone ethylene (ET) plays pivotal role in the regulation of several physiological processes of plants, such as photosynthesis or the accumulation of reactive oxygen- (ROF) or nitrogen forms (RNF). Furthermore, ET is a crucial participant of plant abiotic stress responses. Exogenous ET generators have been used in various studies to evaluate the role of ET in these processes. However, the effect of ET precursor, 1-aminocyclopropane-1-carboxylic acid, which could accumulate in the root zone under natural conditions, was rarely investigated. Thus, the concentration- and/or time dependent influence of exogenous ACC on plants, especially on photosynthesis or on the accumulation of reactive molecules mentioned previously is mostly unknown. The actual ET sensitivity or changes in ET level in tissues, which can be defined as ET status of plants, could be important before or during abiotic stress acclimation. Therefore, the identification of specific processes induced by exogenous ACC, which could alter the physiological response during a subsequent abiotic stress are very important. The abiotic stress induced in plants by high salt concentrations in soil or in irrigation water becomes more significant in the agriculture worldwide with climate change. Thus, the investigation of plant salt stress responses at physiological or molecular level is of great importance. Although ET is an important participant in the regulation of these processes, its effect was mostly investigated during long term salt stress, although the events occurring during the early period of stress acclimation – from hours to few days – determine the fate of the plant later. Furthermore, the data about the connection between plant ET status and ROF/RNF accumulation under short term salt stress are scarce. The role of ET in the regulation of photosynthesis, especially the activity of photosystem I (PSI) under those circumstances mentioned before is barely known. Hence, during our experiments, we used two approaches. First, we investigated the effect of 0.01, 1.0 and 100 µM ACC concentrations applied in hydroponic nutrient solution under non-stress conditions, on major physiological processes of tomato (Solanum lycopersicum L.), which could play a role in abiotic stress acclimation such as photosynthesis, ion accumulation as well as ROF and RNF accumulation. The second approach was divided into two different experimental designs due to technical reasons. Tomato plants with altered ET status, (pre-)treated with 10 µM ACC or ET receptor mutant (Never ripe), were exposed to a growth retarding but tolerable 100 mM or a lethal, 250 mM NaCl concentrations for 24 hours and sampled at multiple time points. We examined the role of ET in early salt stress response by monitoring the parameters mentioned above, and the activity and expression of the most important antioxidant enzymes, which controls oxidative stress

Building definition graphs using monolingual dictionaries of Hungarian

We adapt to Hungarian core functionalitites of the 4lang library [12], which builds 4lang -style semantic representations [7] from raw text using an external dependency parser as proxy, and processes definitions of monolingual dictionaries to build definition graphs for concepts not defined in the hand-written 4lang dictionary [8]. In Section 2 we provide a short overview of the 4lang formalism, Section 3 describes the architecture of the text_to_4lang and dict_to_4lang systems. We describe in detail the steps taken to adapt our system to Hungarian in Section 4. The new tool is evaluated in Section 5. The new components presented in this paper are part of the latest version of the 4lang library, which is available under an MIT license from http://www.github.com/kornai/4lang