755 research outputs found

    First record of Penthalodes ovalis (Dugès, 1834) in agricultural area with notes on its pest status (Acari: Penthalodidae)

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    The first record of species Penthalodes ovalis (Dugès, 1834) in agricultural habitat is presented in this paper. This is also the first record of the occurrence and damages on grown plants. The variability of the morphology and new data on the biology are given as well

    Photoemission Electron Microscopy as a tool for the investigation of optical near fields

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    Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiOx_{x}). Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff ℏωUV=5.0\hbar\omega_{UV}=5.0 eV, wavelength λUV=250\lambda_{UV}=250 nm) and with a Ti:Sapphire femtosecond laser (ℏωl=3.1\hbar\omega_{l}=3.1 eV, λl=400\lambda_{l}=400 nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signature of the local electrical field therefore providing a tool to map the optical near field with the resolution of emission electron microscopy.Comment: 10 pages, 4 figures; submitted to Physical Review Letter

    Supported polysilsesquioxane membrane and production thereof

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    Membranes of the invention comprise a hybrid silica film on a organic polymer support. The silica comprises organic bridging groups bound to two or more silicon atoms, in particular at least 1 of said organic bridging groups per 10 silicon atoms. The membranes can be produced by dry chemistry processes, in particular plasma-enhanced vapour deposition of bridged silane precursors, or by wet chemistry involving hydrolysis of the bridged silane precursors. The membranes are inexpensive and efficient for separation of small molecules and filtration processes

    Photonic mode density effects on single-molecule fluorescence blinking

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    We investigated the influence of the photonic mode density (PMD) on the triplet dynamics of individual chromophores on a dielectric interface by comparing their response in the presence and absence of a nearby gold film. Lifetimes of the excited singlet state were evaluated in ordet to measure directly the PMD at the molecules position. Triplet state lifetimes were simultaneously determined by statistical analysis of the detection time of the fluorescence photons. The observed singlet decay rates are in agreement with the predicted PMD for molecules with different orientations. The triplet decay rate is modified in a fashion correlated to the singlet decay rate. These results show that PMD engineering can lead to an important suppression of the fluorescence, introducing a novel aspect of the physical mechanism to enhance fluorescence intensity in PMD-enhancing systems such as plasmonic devices

    Natural enemies of armored scales (Hemiptera: Diaspididae) and soft scales (Hemiptera: Coccoidae) in Chile: molecular and morphological identification.

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    Scale insects (Hemiptera: Sternorrhyncha: Coccomorpha) are key pests of agricultural crops and ornamental plants worldwide. Their populations are difficult to control, even with insecticides, due to their cryptic habits. Moreover, there is growing concern over the use of synthetic pesticides for their control, due to deleterious environmental effects and the emergence of resistant populations of target pests. In this context, biological control may be an effective and sustainable approach. Hymenoptera Chalcidoidea includes natural enemies of scale insects that have been successfully used in many biological control programs. However, the correct identification of pest scale species and their natural enemies is particularly challenging because these insects are very small and highly specialized. Integrative taxonomy, coupling DNA barcoding and morphological analysis, has been successfully used to characterize pests and natural enemy species. In this study, we performed a survey of parasitoids and predators of armored and soft scales in Chile, based on 28S and COI barcodes. Fifty-three populations of Diaspididae and 79 populations of Coccidae were sampled over the entire length of the country, from Arica (18ËšS) to Frutillar (41ËšS), between January 2015 and February 2016. The phylogenetic relationships obtained by Bayesian inference from multilocus haplotypes revealed 41 putative species of Chalcidoidea, five Coccinellidae and three Neuroptera. Species delimitation was confirmed using ABGD, GMYC and PTP model. In Chalcidoidea, 23 species were identified morphologically, resulting in new COI barcodes for 12 species and new 28S barcodes for 14 species. Two predator species (Rhyzobius lophantae and Coccidophilus transandinus) were identified morphologically, and two parasitoid species, Chartocerus niger and Signiphora bifasciata, were recorded for the first time in Chile
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