Ultrafast Plasmonic Control of Second Harmonic Generation

Efficient frequency conversion techniques are crucial to the development of plasmonic metasurfaces for information processing and signal modulation. In principle, nanoscale electric-field confinement in nonlinear materials enables higher harmonic conversion efficiencies per unit volume than those attainable in bulk materials. Here we demonstrate efficient second-harmonic generation (SHG) in a serrated nanogap plasmonic geometry that generates steep electric field gradients on a dielectric metasurface. An ultrafast pump is used to control plasmon-induced electric fields in a thin-film material with inversion symmetry that, without plasmonic enhancement, does not exhibit an an even-order nonlinear optical response. The temporal evolution of the plasmonic near-field is characterized with ~100as resolution using a novel nonlinear interferometric technique. The ability to manipulate nonlinear signals in a metamaterial geometry as demonstrated here is indispensable both to understanding the ultrafast nonlinear response of nanoscale materials, and to producing active, optically reconfigurable plasmonic device

Influence of Different Packages and Storage Temperatures on the Quality of Edible <i>Allium</i> Species

Allium resources in Russia are a potential source of genes for expanding the genetic base of agricultural crops. The leaves of Allium crops have a short freshness period and quickly deteriorate due to spoilage and loss of water. The aim of the work was to establish the yield and change in the quality of green leaves of Allium species introduced into the Moscow region during short-term storage, depending on the type of packaging, storage period, and temperature. Research methods: introduction and mobilization of existing plant genetic collection of representatives of the genus Allium L. was carried out as part of the implementation of the State task. Four to five-year-old plants of four species (A. altyncolicum, A. chyatophorum, A. nutans and A. turkestanicum) were grown on the collection plot of perennial onions of VNIIO, a branch of the FGBNU FNTSO. In the conditions of the Moscow region, the yield per leaf generation varied from 2.7 kg/m2 (A. altyncolicum) to 4.9 kg/m2 (A. cyathophorum). The maximum yield of marketable products was noted in hermetically sealed plastic bags when stored for 10 days at a temperature of +6 to +8 °C in a refrigerator with controlled conditions: A. turkestanicum—70.0%, A. cyathophorum—75.5%, A. altyncolicum—84.9%, A. nutans—92.9%. The maximum content of vitamin C during storage in hermetic bags with a density of 100 μm was found in A. altyncolicum (37.1 mg per 100 g) and A. nutans (42 mg per 100 g). A slight increase in the amount of sugars after storage for 10 days was noted in species with a linear leaf shape when stored in a polymer box. Temperature control is the most effective approach to extending the shelf life of fresh green leaves by measuring their weight loss and vitamin C

Polycyclic aromatic hydrocarbons in solid residue and volatile organic compounds in snow cover filtrate of Bratsk

Relevance of the study is determined by the need to obtain information on composition of gaseous and particulate air pollutants in the area of ??emission of the main industrial site of Bratsk, where there are large industrial enterprises, such as the production of primary aluminum and pulp and paper mill, thermal power plant, ferroalloy plant. The content of benzo (a) pyrene in aerosols in 2013 in the middle of the city exceeded the norm by three times. The malodorous substances in the surface layer of air reduce as well the quality of life of the population in Bratsk. During the last two or three years in the air of the Central area one can feeel new unpleasant smell, in addition to the familiar but unpleasant smell of sulfur compounds, originating from the pulp and paper industry. Object of the study is snow cover. Research methodology is the snow-chemical survey. Results. In December 2014 the authors selected the snow water filtrate, at the end of February 2015 they selected solid snow sediment samples. The polycyclic aromatic hydrocarbons were determined in snow solid sediment of Bratsk. The authors defined high correlation between the polycyclic aromatic hydrocarbons[h28] compounds in different parts of the emission area, as well as with polycyclic aromatic hydrocarbons[h29] of snow cover in the town with aluminum production - Novokuznetsk, and calculated the ratios for PAH of snow cover in Bratsk, Novokuznetsk and Shelekhov. The indicating ratios (fluoranthene/pyrene, fluoranthene) and (fluoranthene pyrene)/(chrysene+phenanthrene) display the pyrogenic nature of polycyclic aromatic hydrocarbon origin. For the first time the authors determined thirty-nine of volatile organic compounds in the filtrate of snow cover in Bratsk, including natural terpenoids. The coniferous forests or the pine needle processing can be a source of the latter

Polycyclic aromatic hydrocarbons in solid residue and volatile organic compounds in snow cover filtrate of Bratsk

Актуальность исследования определяется необходимостью получения информации о составе газообразных и аэрозольных атмосферных примесей в зоне выбросов основной промышленной площадки Братска, на которой расположены крупные промышленные предприятия, такие как производство первичного алюминия и целлюлозно-бумажный комбинат, предприятия теплоэнергетики, завод ферросплавов. Так, содержание бенз(а)пирена в аэрозолях в 2013 г. в среднем по городу составило 3,3 ПДК. Также снижают качество жизни населения Братска дурнопахнущие вещества в приземном слое атмосферного воздуха, и последние два-три года в воздухе Центрального района ощущался новый неприятный запах, в дополнение к привычным, но неприятным запахам серосодержащих соединений, источником которых является целлюлозно-бумажное производство. Объектом исследования является снежный покров. Методика исследования - снегохимическая съемка. Результаты. В декабре 2014 г. проведен отбор фильтрата снеговой воды, в конце февраля 2015 г. - отбор проб твердого осадка снега. Определены полициклические ароматические углеводороды в твердом осадке снежного покрова Братска, установлена высокая корреляционная связь между составами полициклических ароматических углеводородов в разных точках зоны выбросов, а также с ПАУ снежного покрова города с алюминиевым производством - Новокузнецка. Рассчитаны соотношения для ПАУ снежного покрова Братска, Новокузнецка и Шелехова. Индикаторные соотношения (флуоранте/флуорантен+пирен) и (пирен+флуорантен)/(хризен+фенантрен) указывают на пирогенный характер происхождения ПАУ. Впервые определены тридцать девять легколетучих органических соединений в фильтрате снежного покрова г. Братска, в их числе природные терпеноиды. Источником последних могут быть хвойные леса, или процессы переработки хвои на лесопромышленном комплексе.Relevance of the study is determined by the need to obtain information on composition of gaseous and particulate air pollutants in the area of ??emission of the main industrial site of Bratsk, where there are large industrial enterprises, such as the production of primary aluminum and pulp and paper mill, thermal power plant, ferroalloy plant. The content of benzo (a) pyrene in aerosols in 2013 in the middle of the city exceeded the norm by three times. The malodorous substances in the surface layer of air reduce as well the quality of life of the population in Bratsk. During the last two or three years in the air of the Central area one can feeel new unpleasant smell, in addition to the familiar but unpleasant smell of sulfur compounds, originating from the pulp and paper industry. Object of the study is snow cover. Research methodology is the snow-chemical survey. Results. In December 2014 the authors selected the snow water filtrate, at the end of February 2015 they selected solid snow sediment samples. The polycyclic aromatic hydrocarbons were determined in snow solid sediment of Bratsk. The authors defined high correlation between the polycyclic aromatic hydrocarbons[h28] compounds in different parts of the emission area, as well as with polycyclic aromatic hydrocarbons[h29] of snow cover in the town with aluminum production - Novokuznetsk, and calculated the ratios for PAH of snow cover in Bratsk, Novokuznetsk and Shelekhov. The indicating ratios (fluoranthene/pyrene, fluoranthene) and (fluoranthene pyrene)/(chrysene+phenanthrene) display the pyrogenic nature of polycyclic aromatic hydrocarbon origin. For the first time the authors determined thirty-nine of volatile organic compounds in the filtrate of snow cover in Bratsk, including natural terpenoids. The coniferous forests or the pine needle processing can be a source of the latter

Комплексная разработка методов повышения эффективности обработки труднообрабатываемых материалов за счет совершенствования режущих инструментов и условий их применения

В ходе проведенной научно-исследовательской работы разработана конечно-элементная модель труднообрабатываемого многокомпонентного (композиционного) материала. Предложены и внедрены экспериментальные методики определения физико-механических и трибологических свойств и моделей многокомпонентных материалов. Исследовано и обосновано влияние различных факторов на силу и температуру резания, механические повреждения поверхностей отверстий в пакетах углепластик/металл на границе между слоями пакета. Теоретические положения доведены до уровня конкретных методик и практических рекомендаций, которые создают условия для внедрения в производство