565 research outputs found
Coupled surface plasmon-polariton mediated photoluminescence from a top-emitting organic light-emitting structure
Copyright © 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 85 (2004) and may be found at http://link.aip.org/link/?APPLAB/85/182/1We report strong photoluminescence from a top-emitting organic light-emitting structure where emission takes place through a thin (55 nm) silver film. We show that this emission is mediated via coupled surface plasmon-polariton modes. Our results show that the addition of a dielectric grating to otherwise planar structures, such as surface-emitting organic light-emitting diodes, may offer a way to increase the external efficiency of top-emitting organic light-emitting diodes
Bioassay-guided isolation and identification of antimicrobial compounds from thyme essential oil by means of overpressured layer chromatography, bioautography and GC-MS
A simple method is described for efficient isolation of compounds having an antibacterial effect.
Two thyme (Thymus vulgaris) essential oils, obtained from the market, were chosen as
prospective materials likely to feature several bioactive components when examined by thin layer
chromatography coupled with direct bioautography as a screening method. The newly developed
infusion overpressured layer chromatographic separation method coupled with direct
bioautography assured that only the active components were isolated by means of overrun
overpressured layer chromatography with online detection and fractionation. Each of the 5
collected fractions represented one of the five antimicrobial essential oil components designated
at the screening. The purity and the activity of the fractions were confirmed with chromatography
coupled various detection methods (UV, vanillin-sulphuric acid reagent, direct bioautography).
The antibacterial components were identified with GC-MS as thymol, carvacrol, linalool, diethylphthalate,
and alpha-terpineol. The oil component diethyl-phthalate is an artificial compound,
used as plasticizer or detergent bases in the industry. Our results support that exploiting its
flexibility and the possible hyphenations, overpressured layer chromatography is especially
attractive for isolation of antimicrobial components from various matrixes
Evaluation of CAY-1, an Experimental, Natural Fungicide, For Control of Strawberry Pathogens
CAY-1 is an experimental, natural product being tested as a potential fungicide. This saponin isolated from Capsicum frutescens interacts with membrane sterols causing leakage of cell components and ultimately cell death in a variety of fungi. CAY-1 and the commercial fungicide captan were tested in an in vitro doseresponse dilution-broth assay. They caused at least 85% growth inhibition of the fungal pathogens Colletotrichum acutatum, C fragariae and C. gloeosporioides when tested at 3.0 μM. Even though CAY-1 strongly reduced the growth of these fungal pathogens in laboratory assays and prevented anthracnose development in detached leaf assays, it did not control foliar or fruit rot diseases of strawberry in field trials
Natural Toxins for Use in Pest Management
Natural toxins are a source of new chemical classes of pesticides, as well as environmentally and toxicologically safer molecules than many of the currently used pesticides. Furthermore, they often have molecular target sites that are not exploited by currently marketed pesticides. There are highly successful products based on natural compounds in the major pesticide classes. These include the herbicide glufosinate (synthetic phosphinothricin), the spinosad insecticides, and the strobilurin fungicides. These and other examples of currently marketed natural product-based pesticides, as well as natural toxins that show promise as pesticides from our own research are discussed
Antifungal fatty acids produced by Coniochaeta ligniaria: a cryptic endophytic fungus associated with Smallanthus sonchifolius' autotrophic cultures.
Resonant absorption of electromagnetic fields by surface plasmons buried in a multilayered plasmonic nanostructure
Alastair P. Hibbins, W. Andrew Murray, J. Tyler, S. Wedge, William L. Barnes, and J. Roy Sambles, Physical Review B, Vol. 74, article 073408 (2006). "Copyright © 2006 by the American Physical Society."The optical reflectivity of a metal-dielectric-metal microcavity in which the upper layer is periodically perforated by narrow slits is explored. Complete characterization of the observed modes in terms of their resonant electromagnetic fields is achieved by comparison of the experimental data to the predictions of a finite-element model. In particular, we demonstrate that the slits provide efficient diffractive coupling to a surface plasmon mode buried within the microcavity whose propagation is strongly confined to the dielectric layer
Identification and characterization of an irreversible inhibitor of CDK2
Irreversible inhibitors that modify cysteine or lysine
residues within a protein kinase ATP binding site offer, through their distinctive mode of action, an alternative to ATP-competitive agents. 4-((6-(Cyclohexylmethoxy)-
9H-purin-2-yl)amino)benzenesulfonamide (NU6102) is a potent and selective ATP-competitive inhibitor of CDK2 in which the sulfonamide moiety is positioned close to a pair of lysine residues. Guided by the CDK2/NU6102 structure, we designed 6-(cyclohexylmethoxy)-N-(4-(vinylsulfonyl)phenyl)-9H-purin-2-amine (NU6300), which binds covalently to CDK2 as shown by a co-complex crystal
structure. Acute incubation with NU6300 produced a durable inhibition of Rb phosphorylation in SKUT-1B cells, consistent with it acting as an irreversible CDK2 inhibitor. NU6300 is the first covalent CDK2 inhibitor to be described, and illustrates the potential of vinyl sulfones for the design of more potent and selective compounds
Sampling-based Algorithms for Optimal Motion Planning
During the last decade, sampling-based path planning algorithms, such as
Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have
been shown to work well in practice and possess theoretical guarantees such as
probabilistic completeness. However, little effort has been devoted to the
formal analysis of the quality of the solution returned by such algorithms,
e.g., as a function of the number of samples. The purpose of this paper is to
fill this gap, by rigorously analyzing the asymptotic behavior of the cost of
the solution returned by stochastic sampling-based algorithms as the number of
samples increases. A number of negative results are provided, characterizing
existing algorithms, e.g., showing that, under mild technical conditions, the
cost of the solution returned by broadly used sampling-based algorithms
converges almost surely to a non-optimal value. The main contribution of the
paper is the introduction of new algorithms, namely, PRM* and RRT*, which are
provably asymptotically optimal, i.e., such that the cost of the returned
solution converges almost surely to the optimum. Moreover, it is shown that the
computational complexity of the new algorithms is within a constant factor of
that of their probabilistically complete (but not asymptotically optimal)
counterparts. The analysis in this paper hinges on novel connections between
stochastic sampling-based path planning algorithms and the theory of random
geometric graphs.Comment: 76 pages, 26 figures, to appear in International Journal of Robotics
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