1,494 research outputs found

    Pseudospin dynamics in multimode polaritonic Josephson junctions

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    We analyzed multimode Josephson junctions with exciton-polaritons (polaritonic Josephson junctions) when several coupling mechanisms of fundamental and excited states are present. The applied method is based on Keldysh-Green function formalism and takes into account polariton pseudospin. We found that mean value of circular polarization degree in intrinsic Josephson oscillations and microscopic quantum self-trapping follow an oscillator behavior whose renormalizes due to intermode interactions. The effect of an additional transfer of particles over junction barrier occurring in multimode approximation in combination with common Josephson tunneling is discussed in regime of dynamical separation of two polarizations.Comment: 12 pages, 4 figure

    Technical product risk assessment: Standards, integration in the erm model and uncertainty modeling

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    European Union has accomplished, through introducing New Approach to technical harmonization and standardization, a breakthrough in the field of technical products safety and in assessing their conformity, in such a manner that it integrated products safety requirements into the process of products development. This is achieved by quantifying risk levels with the aim of determining the scope of the required safety measures and systems. The theory of probability is used as a tool for modeling uncertainties in the assessment of that risk. In the last forty years are developed new mathematical theories have proven to be better at modeling uncertainty when we have not enough data about uncertainty events which is usually the case in product development. Bayesian networks based on modeling of subjective probability and Evidence networks based on Dempster-Shafer theory of belief functions proved to be an excellent tool for modeling uncertainty when we do not have enough information about all events aspect

    Electric generation of vortices in an exciton-polariton superfluid

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    We have theoretically demonstrated the on demand electric generation of vortices in an exciton-polariton superfluid. Electric pulses applied to a horseshoe-shaped metallic mesa, deposited on top of the microcavity, generate a non-cylindrically symmetric solitonic wave in the system. Breakdown of its wavefront at focal points leads to the formation of vortex-antivortex pairs which subsequently propagate in the superfluid. The trajectory of these vortex dipoles can be controlled by applying a voltage to additional electrodes. They can be confined within channels formed by metallic stripes and unbound by a wedged mesa giving birth to grey solitons. Finally single static vortices can be generated using a single metallic plate configuration.Comment: 7 pages and 7 figure

    Acid aging effects on surfaces of PTFE gaskets investigated by thermal analysis

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    This paper investigates the effect of a prolonged acid attack on the surface of PTFE by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). PTFE is very non-reactive, partly because of the strength of carbon\u2013fluorine bonds and for its high crystallinity, and, as a consequence, it is often used in containers and pipework with reactive and corrosive chemicals. The PTFE under analysis is commercialized by two alternative producers in form of Teflon tapes. These tapes are adopted, as gaskets, in process plants where tires moulds are cleaned by acid solutions inside a multistage ultrasonic process. In this case, PTFE shows, in a relatively short operation time, inexplicably phenomena of surface degradation, which could be related, in general terms, to an acid attack. But, even considering the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the risk of the extreme erosion phenomena as observed. The present experimental research aim at investigating this contradiction. A possible explanation could be related to the presence in the cleaning solution of unexpected fluorides, able to produce fluorinating agents and, thus, degrade carbon-fluorine bonds. Considering more the 300 chemical elements a tire compound consists in, it is really complex to preserve the original chemical composition of the cleaning solution. In this research PTFE samples have been treated with different mixtures of acids with the aim at investigating the different aging effects. The thermal analysis has permitted the experimental characterization of PTFE surface properties after acid attack, providing evidence of the degradation phenomena. In particular, the different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but also differences between manufacturers

    Influence of Altitude on Phytochemical Composition of Hemp Inflorescence: A Metabolomic Approach

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    The phytochemical profiling of hemp inflorescences of clonal plants growing in different conditions related to altitude was investigated. Four strains of industrial hemp (Cannabis sativa L., family Cannabaceae) of Kompolti variety were selected and cloned to provide genetically uniform material for analyses of secondary metabolites (terpenes, cannabinoids, and flavonoids) at two different elevations: mountain (Alagna Valsesia 1200 m ASL) and plains (Vercelli Province 130 m ASL). Environmental conditions influenced by elevation have proven to be important factors inducing variations in hemp inflorescences\u2019 secondary metabolite composition. In fact, all plants grown at altitude exhibited a higher total amount of terpenes when compared with plains counterparts, with \u3b2-Myrcene, trans-Caryophyllene and \u3b1-Humulene as the main contributors. A metabolomic, un-targeted approach performed by HPLC-Q-Exactive-Orbitrap\uae-MS platform with subsequent data processing performed by Compound DiscovererTM software, was crucial for the appropriate recognition of many metabolites, clearly distinguishing mountain from plains specimens. Cannabidiolic acid CBDA was the most abundant phytocannabinoid, with significantly higher concentrations in the mountain samples. The metabolic pathway of CBGA (considered as the progenitor/precursor of all cannabinoids) was also activated towards the production of CBCA, which occurs in considerably 3 times higher quantities than in the clones grown at high altitude. Isoprenoid flavones (Cannaflavins A, B, and C) were correspondingly upregulated in mountain samples, while apigenin turned out to be more abundant in plains samples. The possibility to use hemp inflorescences in pharmaceutical/nutraceutical applications opens new challenges to understand how hemp crops respond in terms of secondary metabolite production in various environments. In this regard, our results with the applied analytical strategy may constitute an effective way of phytochemical profiling hemp inflorescences

    Gene expression profiles among murine strains segregate with distinct differences in the progression of radiation-induced lung disease.

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    Molecular mechanisms underlying development of acute pneumonitis and/or late fibrosis following thoracic irradiation remain poorly understood. Here, we hypothesize that heterogeneity in disease progression and phenotypic expression of radiation-induced lung disease (RILD) across murine strains presents an opportunity to better elucidate mechanisms driving tissue response toward pneumonitis and/or fibrosis. Distinct differences in disease progression were observed in age- and sex-matched CBA/J, C57L/J and C57BL/6J mice over 1 year after graded doses of whole-thorax lung irradiation (WTLI). Separately, comparison of gene expression profiles in lung tissue 24 h post-exposure demonstrated \u3e5000 genes to be differentially expressed (P\u3c0.01; \u3etwofold change) between strains with early versus late onset of disease. An immediate divergence in early tissue response between radiation-sensitive and -resistant strains was observed. In pneumonitis-prone C57L/J mice, differentially expressed genes were enriched in proinflammatory pathways, whereas in fibrosis-prone C57BL/6J mice, genes were enriched in pathways involved in purine and pyrimidine synthesis, DNA replication and cell division. At 24 h post-WTLI, different patterns of cellular damage were observed at the ultrastructural level among strains but microscopic damage was not yet evident under light microscopy. These data point toward a fundamental difference in patterns of early pulmonary tissue response to WTLI, consistent with the macroscopic expression of injury manifesting weeks to months after exposure. Understanding the mechanisms underlying development of RILD might lead to more rational selection of therapeutic interventions to mitigate healthy tissue damage

    On the new very early table varieties obtained by crossing different varieties of grapevine

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    In order to obtain new table grape varieties which ripen before or at the same time as variety Pearl of Csaba, we performed many intervarietal crossings at our experimental station, using the following parents: Pearl of Csaba, Chasselas Bouvier, Muscat Ottonel, Queen of Vineyard, Cardinal, Dattier de Beyrouth, Ribier.The Government Commission acknowledged five very early varieties, three of which have also better agrobiological and technological characteristics than the variety Pearl of Csaba.The new variety Demir Door ripens on average 6 d, the new variety Early of Belgrade 3-5 d earlier, and the new variety Grochanka ripens at the same time or 1-3 d later as the control variety Pearl of Csaba.Due to multiple regression analysis, biological characteristics as yield, cluster and berry weights and sugar content strongly depend on meteorological conditions (temperature, rainfall and solar radiation); this is valid for all the new varieties and the variety Pearl of Csaba at all locations investigated.Analysis of variance (level of 0.05 and 0.01) shows that compared to the control variety we obtained with new varieties significantly greater yields, very significant large cluster and berry weights and very significantly better uvological characteristics of berry. The average yields for all investigated locations were increased in comparison to the control variety Pearl of Csaba: Demir Door +3.004 kg/ha, Early of Belgrade +6.259 kg/ha, Grochanka +7.065 kg/ha.Organoleptic characteristics are much improved with all new varieties which is illustrated by increased indexes.All investigated varieties are acknowledged genotypes of Vitis vinifera L, and all of these new varieties exhibited better biological and technological parameters than Pearl of Csaba

    Cr3+ substituted Zn-Al layered double hydroxides as UV–Vis light photocatalysts for NO gas removal from the urban environment

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    The ZnAl-CO3, ZnAlCr-CO3 and ZnCr-CO3 LDH samples were studied as De-NOx photocatalysts in this work. Samples without Cr and increasing the presence of Cr3+ in the LDH framework in the 0.06, 0.15 and 0.3 Cr/Zn ratio were prepared by co-precipitation method, all of them constituted by pure LDH phase. The increase of chromium content in the LDH framework leads to lower crystallinity and higher specific surface area in the samples. Moreover, the CrO6 octahedron centres expand the photo-activity from UV to Visible light and assist to decrease the recombination rate of the electrons and holes. The favourable textural, optical and electronic properties of Cr-containing LDH samples explain the good NO removal efficiency (55%) and outstanding selectivity (90%) found for the analysed De-NOx process
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