Kinetics of exciton photoluminescence in type-II semiconductor superlattices

The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the plane interface and at the roughness. Expressions that relate the parameters of the luminescence kinetics with statistical characteristics of the rough interface are obtained. The mean height and length of roughnesses in GaAs/AlAs superlattices are estimated from the experimental data.Comment: 3 PostScript figure

Influence of substrate types and reflector proximities over a NDTC antenna

The influence of dissimilar substrates and reflector proximities over a newly developed Non-uniformly Distributed-Turns Coil (NDTC) antenna for High-Frequency (HF) Radio Frequency IDentification (RFID) applications is presented. In the study, the performance of the HF-RFID NDTC antenna over various substrates with deposited conductor thicknesses is conducted. In addition, the effect over a conceivably encountered reflector in the proximity of the antenna is considered. Insensitive reflection coefficient (S11) responses for different substrate permittivities were experienced and the diverse conductor types and thicknesses contributed to a compromised magnetic-field (H-field) and recalculated matching network. The matching network additionally preserves resonance when the antennas is in close proximity to the reflector and a predictable H-field response for the separation range is shown

Influence of climatic variables on crown condition in pine forests of Northern Spain

Producción CientíficaThe aim of this study was to find relationships between crown condition and some climatic parameters to identify which are those having a main influence on crown condition, and how this influence is shown in the tree (crown transparency), and to contribute to the understanding of how these parameters will affect under future climate change scenarios

Space Architecture: The Role, Work and Aptitude

Space architecture has been an emerging discipline for at least 40 years. Has it arrived? Is space architecture a legitimate vocation or an avocation? If it leads to a job, what do employers want? In 2002, NASA Headquarters created a management position for a space architect whose job was to "lead the development of strategic architectures and identify high level requirements for systems that will accomplish the Nation's space exploration vision." This is a good job description with responsibility at the right level in NASA, but unfortunately, the office was discontinued two years later. Even though there is no accredited academic program or professional licensing for space architecture, there is a community of practitioners. They are civil servants, contractors and academicians supporting International Space Station and space exploration programs. In various ways, space architects currently contribute to human spaceflight, but there is a way for the discipline to be more effective in developing solutions to large scale complex problems. This paper organizes contributions from engineers, architects and psychologists into recommendations on the role of space architects in the organization, the process of creating and selecting options, and intrinsic personality traits including why they must have a high tolerance for ambiguity

Investigation of the Influence of Antioxidant Compositions on Development of Microbiological Spoilage in Storage of Fruits

The studies are devoted to the scientific grounding of expedience of after-harvest processing by antioxidant compositions for preventing the development of pathogenic microflora on fruit surfaces during a long storage. For the studies were used apple fruits of the varieties Aidared, Golden Dushesse, Renet Simirenka, pear fruits of the varieties Victoria, Crimea Raisin and Cure, plum fruits of the varieties Voloshka, Stanley and Italian Ugorka. Fruits were processed by immersion in the following antioxidant compositions: ACM is a mixture of dimethyl sulfoxide, ionol and polyethylene glycols; AARL – mixture of ascorbic acid, routin and lecithin; DL – mixture of dimethyl sulfoxide, ionol and lecithin. Fruits, processed by water, were used as a control. Exposition - 10 seconds. Storage was carried out at the temperature 0±1 ºС, relative air humidity 90–95 %. It was established that in the period of fruits laying for storage, the mean amount of epiphyte microflora was fixed on surfaces of plump and pear fruits of the mean ripening term. In the variety composition of epiphyte microflora prevailed spores of mesophyl aerobic and facultative-anaerobic microorganisms. Their mean number on apple fruits surface was 9,6·103 CCU/g, pear fruits – 10,6 103 CCU/g, plump fruits – 18·103CCCU/g. AOC processing of all types of fruits essentially decreased the speed of both MAFAnM and micromycetes growth. It was demonstrated that the used compositions in 2…3,5 times decreased the level of day losses from microbiological spoilage during the whole storage period. The most positive effect was received at using compositions, based on dystinol and lecithin. Multifactor analysis determined that the level of day losses from microbiological spoilage was mainly influenced by factors of raw material variety features (factor A) and antioxidant compositions processing (factor D). The shares of influence are 24 and 21 % respectively

Investigation of the Cinnamon Influence on the Wheat Bread Quality Enriched with Flax Seeds Oil Meal

The materials of the article are studies that are conducted with the aim of expanding the use of non-traditional raw materials for functional purposes in the technology of bakery products. Research is conducted to determine the effect of spiciness cinnamon on the quality of semi-finished products and finished bakery products from wheat flour enriched with flax seeds oil meal.To improve the quality of wheat bread, enriched with flax seeds oil meal, and expand the assortment of bakery products with health properties, the authors propose to use spice cinnamon in the formula of wheat bread in an amount of up to 2 % of the weight of flour. The taste and aroma of these products is characteristic of wheat bread with a pleasant cinnamon flavor. Dosage of cinnamon to 4 % of the flour mass also provides good consumer characteristics of products, however, more pronounced flavor and flavor of cinnamon can limit the circle of consumers of such products. The use of 6 % of cinnamon in the recipe of products leads to a significant deterioration in the volume of products and provides them with too intense flavor. Determination of the content of bisulphite-binding substances in the crumb and crust of products is confirmed by improvements in the fragrance of products with the addition of cinnamon.It has been established that the cinnamon in dough leads to an increase in the elastic properties of gluten, and the more, the more it is added. Along with this, it is noted that cinnamon leads to a decrease in the fermentation intensity of the dough. This is probably due to the active antibacterial properties of cinnamon, which suppress the yeast fermentation activity. These factors and cause the deterioration of the volume of finished products in the case of dosing cinnamon in an amount of 4 % or more.It has been proved that on the indicators of crumbling and deformation of the crumb, products with added cinnamon retain their freshness similarly to the control one. However, it is noted that the introduction of cinnamon reduces the amount of mold of microflora in products