Composição e abundância de peixes da interface entre as águas abertas e bancos de macrófitas e sua dinâmica nos períodos de crepúsculos matutino e vespertino, no lago Catalão, Amazonas, Brasil (Composition and abundance of fishes in the interface between open water and macrophyte banks, and the dynamics of this interface during morning and evening twilight, in lake Catalao, Amazonas, Brazil)

This work studied the composition and abundance of the fishes that move between macrophyte banks and open water during the morning twilight (CM) and afternoon twilight (CV). The collections were made using gillnets, along banks of Paspalum repens, at Catalão lake, in Amazonas, Brazil. A total of 222 individuals and 37 species were collected. Of these, 130 individuals were collected during the CM and 92 during the CV; 80 individuals were leaving during the CM and 40 individuals were leaving during the CV. Auchenipterus nuchalis, Pellona castelnaeana, Triportheus angulatus and T. albus were the most common and concentrated species collected in the CM and Pimelodus blochii was the most common species collected in the CV

Impact on the Population of the Triplet Excited State

Publisher Copyright: © 2022 American Chemical Society. All rights reserved.Two series of dinuclear gold(I) complexes that contain two Au-chromophore units (chromophore = dibenzofurane or dimethylfluorene) connected through a diphosphane bridge that differs in the flexibility and length (diphosphane = dppb for 1,4-bis(diphenylphosphino)butane, DPEphos for bis[(2-diphenylphosphino)phenyl]ether, xanthphos for 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and BiPheP for 2,2′-bis(diphenylphosphino)-1,1′-biphenyl) have been synthesized and structurally characterized. Their photophysical properties have been carefully investigated, paying attention to the role of the presence, or absence, of aurophilic contacts and their nature (intra- or intermolecular character). This analysis was permitted due to the X-ray crystallographic determination of all of the structures of the compounds discussed herein. The quantum yields of the triplet population, φT, have been calculated by nanosecond-laser flash photolysis measurements, and we could determine the main role of the character of the aurophilic contacts in the resulting φT, being especially favored in the presence of intermolecular contacts. Time-dependent density functional theory (TD-DFT) calculations support the absorption and emission assignments and the shorter distance between S1and the closest triplet excited state energy in the case of the compounds with a higher triplet-state population.publishersversionpublishe

Intra- vs Intermolecular Aurophilic Contacts in Dinuclear Gold(I) Compounds: Impact on the Population of the Triplet Excited State

Two series of dinuclear gold(I) complexes that contain two Au–chromophore units (chromophore = dibenzofurane or dimethylfluorene) connected through a diphosphane bridge that differs in the flexibility and length (diphosphane = dppb for 1,4-bis(diphenylphosphino)butane, DPEphos for bis[(2-diphenylphosphino)phenyl]ether, xanthphos for 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, and BiPheP for 2,2′-bis(diphenylphosphino)-1,1′-biphenyl) have been synthesized and structurally characterized. Their photophysical properties have been carefully investigated, paying attention to the role of the presence, or absence, of aurophilic contacts and their nature (intra- or intermolecular character). This analysis was permitted due to the X-ray crystallographic determination of all of the structures of the compounds discussed herein. The quantum yields of the triplet population, ϕT, have been calculated by nanosecond-laser flash photolysis measurements, and we could determine the main role of the character of the aurophilic contacts in the resulting ϕT, being especially favored in the presence of intermolecular contacts. Time-dependent density functional theory (TD-DFT) calculations support the absorption and emission assignments and the shorter distance between S1 and the closest triplet excited state energy in the case of the compounds with a higher triplet-state population

Room-Temperature Phosphorescence and Efficient Singlet Oxygen Production by Cyclometalated Pt(II) Complexes with Aromatic Alkynyl Ligands

The synthesis of five novel cyclometalated platinum(II) compounds containing five different alkynyl-chromophores was achieved by the reaction of the previously synthesized Pt-Cl cyclometalated compound (1) with the corresponding RC (math)CH by a Sonogashira reaction. It was observed that the spectral and photophysical characteristics of the cyclometalated platinum(II) complexes (Pt-Ar) are essentially associated with the platinum-cyclometalated unit. Room-temperature emission of the Pt-Ar complexes was attributed to phosphorescence in agreement with DFT calculations. Broad nanosecond (ns)-transient absorption spectra were observed with decays approximately identical to those obtained from the emission of the triplet state. From the femtosecond-transient absorption (fs-TA) data, two main excited- state decay components were identified: one in the order of a few picoseconds was assigned to fast intersystem crossing to populate the triplet excited-state and the second (hundreds of ns) was associated with the decay of the transient triplet state. In general, efficient singlet oxygen photosensitization quantum yields were observed from the triplet state of these complexes

Solar wind speed theory and the nonextensivity of solar corona

The solar corona is a complex system, with nonisothermal plasma and being in the self-gravitating field of the Sun. So the corona plasma is not only a nonequilibrium system but also a nonextensive one. We estimate the parameter of describing the degree of nonextensivity of the corona plasma and study the generalization of the solar wind speed theory in the framework of nonextensive statistical mechanics. It is found that, when use Chapman's corona model (1957) as the radial distribution of the temperature in the corona, the nonextensivity reduces the gas pressure outward and thus leads a significant deceleration effect on the radial speed of the solar wind.Comment: 12 pages,1 figure, 1 table, 21 references; UN/ESA/NASA Workshop on Basic Space Science and the International Heliophysical Year 2007, National Astronomical Observatory of Japan, 18-22 June, 2007, Tokyo, Japa

Accretions of Various Types of Dark Energies onto Morris-Thorne Wormhole

In this work, we have studied accretion of the dark energies onto Morris-Thorne wormhole. For quintessence like dark energy, the mass of the wormhole decreases and phantom like dark energy, the mass of wormhole increases. We have assumed two types of dark energy like variable modified Chaplygin gas (VMCG) and generalized cosmic Chaplygin gas (GCCG). We have found the expression of wormhole mass in both cases. We have found the mass of the wormhole at late universe and this is finite. For our choices the parameters and the function $B(a)$, these models generate only quintessence dark energy (not phantom) and so wormhole mass decreases during evolution of the universe. Next we have assumed 5 kinds of parametrizations of well known dark energy models. These models generate both quintessence and phantom scenarios. So if these dark energies accrete onto the wormhole, then for quintessence stage, wormhole mass decreases upto a certain value (finite value) and then again increases to infinite value for phantom stage during whole evolution of the universe. We also shown these results graphically.Comment: 9 pages, 7 figures. arXiv admin note: text overlap with arXiv:1112.615