Cytoembryological and morphometric characteristics of some Armenian grape cultivars

Research Not

Preliminary study of Armenian grapevines phenolic contents

Research Not

Armenian grapevines: cytoembryological, morphological and chemical analysis

The objectives of our study was to phenotype Armenian grapevines on the base of cytoembryological, morphometric and phenolic content analysis of 10 wine and 10 table cultivars (Vitis vinifera L.). The presented results suggest that Armenian table grape cultivars have higher level of abnormalities in the process of seed formation than wine cultivars. However, during ovule development, the observed differences between table and wine varieties were not significant. The berry morphometric analysis demonstrated that table cultivars formed significantly larger and heavier berries than wine cultivars. The obtained results show that wine grapes contained significantly higher phenol concentrations than table grapes, in both colored and white grapevine cultivars. The study of phenol composition, an important chemical descriptor in grapevine phenotyping, provides oenological information useful to improve the wine quality. Cultivar characterization could be used as marker for the selection of table and wine grape breeding programs. These results will be upgraded in the database for Armenian grapevine varieties. In future Armenian germplasm will be compared with datasets of neighboring countries, to determine the varietal origins relationships

Genetic analysis of the VvMybA1 gene in Armenian grapevines (V. Vinifera L.)

Research Not

DNA Copy Number Variations as Markers of Mutagenic Impact

DNA copy number variation (CNV) occurs due to deletion or duplication of DNA segments resulting in a different number of copies of a specific DNA-stretch on homologous chromosomes. Implications of CNVs in evolution and development of different diseases have been demonstrated although contribution of environmental factors, such as mutagens, in the origin of CNVs, is poorly understood. In this review, we summarize current knowledge about mutagen-induced CNVs in human, animal and plant cells. Differences in CNV frequencies induced by radiation and chemical mutagens, distribution of CNVs in the genome, as well as adaptive effects in plants, are discussed. Currently available information concerning impact of mutagens in induction of CNVs in germ cells is presented. Moreover, the potential of CNVs as a new endpoint in mutagenicity test-systems is discussed

Fluctuation-enhanced gas sensing

AbstractThe sensitivity of gas sensors was earlier measured by classical method-comparison the resistance of sensors in gas media and air. Here we reported results of the study of low-frequency noise characteristics of sensors. We compare data for different Figaro TGS sensors as well as our sol-gel H2 tin dioxide and porous silicon sensors. The study was performed in dry air and in a mix of dry air with carbon monoxide, hydrogen and alcohol of different concentrations. Higher sensitivity of spectral dependence of noise (SDN) to gas concentration in comparison with classical method of the measurements of gas sensing by a change in the Ohmic resistance part of current-voltage characteristics of samples allows using such SND powerful method for determination of gas concentration in the air or environment

Growth process, characterization, and modeling of electronic properties of coupled InAsSbP nanostructures

Quaternary III-V InAsSbP quantum dots (QDs) have been grown in the form of cooperative InAsSb/InAsP structures using a modified version of the liquid phase epitaxy. High resolution scanning electron microscopy, atomic force microscopy, and Fourier-transform infrared spectrometry were used to investigate these so-called nano-camomiles, mainly consisting of a central InAsSb QD surrounded by six InAsP-QDs, that shall be referred to as leaves in the following. The observed QDs average density ranges from 0.8 to 2 x 10(9) cm(-2), with heights and widths dimensions from 2 to 20 nm and 5 to 45 nm, respectively. The average density of the leaves is equal to (6-10) x 10(9) cm(-2) with dimensions of approx. 5 to 40 nm in width and depth. To achieve a first basic understanding of the electronic properties, we have modeled these novel nanostructures using second-order continuum elasticity theory and an eight-band k . p model to calculate the electronic structure. Our calculations found a clear localization of hole states in the central InAsSb dot. The localization of electron states, however, was found to be weak and might thus be easily influenced by external electric fields or strain. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3624621

CO Gas Adsorption on SnO2 Surfaces: Density Functional Theory Study

This research is devoted to the investigation of the toxic carbon monoxide gas adsorption mechanisms on the tin dioxide semiconductor. We used density functional theory to describe adsorption processes and found out that the Mars- van Krevelen adsorption mechanism is not responsible for adsorption on (101) and (001) surface orientations of tin dioxide. For (110) and (100) surfaces, after adsorption carbon dioxide molecule forms and desorbs from the surfaces. For (101) surface orientation, carbon monoxide adsorb to the surface’s oxide by carbon atom and stay bonded to it. Charge transfer from the molecule to the surface, which equal to 1.9e calculated by Bader charge analysis. In the case of (001) surface orientation, carbon monoxide adsorb to surface’s oxygen and stay bonded too. Here, we consider half and full surface coverages. It was shown, that during full surface coverage, only one molecule can adsorbs and transfer 2e charge. Electronic density of states calculation was done to explain the increase of surface conductance