Grape seed procyanidins prevent oxidative injury by modulating the expression of antioxidant enzyme systems   总被引：7，自引：0，他引：7  

Puiggros F  Llópiz N  Ardévol A  Bladé C  Arola L  Salvadó MJ 《Journal of agricultural and food chemistry》2005,53(15):6080-6086

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Antioxidant activity of olive pulp and olive oil phenolic compounds of the arbequina cultivar   总被引：3，自引：0，他引：3  

Morelló JR  Vuorela S  Romero MP  Motilva MJ  Heinonen M 《Journal of agricultural and food chemistry》2005,53(6):2002-2008

The aim of this study was to characterize antioxidant activities of phenolic compounds that appear in olive pulp and olive oils using both radical scavenging and antioxidant activity tests. Antiradical and antioxidant activities of olive pulp and olive oil phenolic compounds were due mainly to the presence of a 3,4-dihydroxy moiety linked to an aromatic ring, and the effect depended on the polarity of the phenolic compound. Glucosides and more complex phenolics exhibited higher antioxidant activities toward oxidation of liposomes, whereas in bulk lipids aglycons were more potent antioxidants with the exception of oleuropein. Lignans acted as antioxidants only in liposomes, which could partly be due to their chelating activity, because liposome oxidation was initiated by cupric acetate. The antioxidant activity of virgin olive oil is principally due to the dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), a secoiridoid derivative (peak RT 36, structure unidentified), and luteolin.  相似文献   

Characterization of mammalian selenoproteomes   总被引：3，自引：0，他引：3  

Kryukov GV  Castellano S  Novoselov SV  Lobanov AV  Zehtab O  Guigó R  Gladyshev VN 《Science (New York, N.Y.)》2003,300(5624):1439-1443

In the genetic code, UGA serves as a stop signal and a selenocysteine codon, but no computational methods for identifying its coding function are available. Consequently, most selenoprotein genes are misannotated. We identified selenoprotein genes in sequenced mammalian genomes by methods that rely on identification of selenocysteine insertion RNA structures, the coding potential of UGA codons, and the presence of cysteine-containing homologs. The human selenoproteome consists of 25 selenoproteins.  相似文献   

Properties of metallic nanowires: from conductance quantization to localization     

Pascual JI  Méndez J  Gómez-Herrero J  Baró AM  Garcia N  Landman U  Luedtke WD  Bogachek EN  Cheng HP 《Science (New York, N.Y.)》1995,267(5205):1793-1795

Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2).  相似文献   

Selective and efficient platinum(0)-carbene complexes as hydrosilylation catalysts     

Markó IE  Stérin S  Buisine O  Mignani G  Branlard P  Tinant B  Declercq JP 《Science (New York, N.Y.)》2002,298(5591):204-206

The hydrosilylation reaction enables the production of silicon polymers. Platinum-carbene complexes are reported that catalyze the hydrosilylation reaction of alkenes with remarkable efficiency and exquisite selectivity and avoid the formation of platinum colloids. By-products, typically encountered with previous catalytic systems, are suppressed with these platinum derivatives.  相似文献   

NANOTECHNOLOGY: Beyond Gedanken Experiments     

Forró L 《Science (New York, N.Y.)》2000,289(5479):560-561

For future nanomechanical devices to be realized, sophisticated ways of manipulating small structures must be developed, and fundamental elements of macroscopic machines, such as switches and bearings, must be reproduced in the nanoscale. Forró highlights the nanotube nanobearings and nanoswitches reported by Cumings and Zettl and concludes that multiwall nanotubes are ideal starting materials for future nanodevices.  相似文献   

Spain's Ramón y Cajal Program     

Axness C  Tornero P  Ricote J  Algueró M 《Science (New York, N.Y.)》2003,300(5616):52-53

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Ecology. Dipping into the rare biosphere     

Pedrós-Alió C 《Science (New York, N.Y.)》2007,315(5809):192-193

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Electronic transitions in perovskite: possible nonconvecting layers in the lower mantle     

Badro J  Rueff JP  Vankó G  Monaco G  Fiquet G  Guyot F 《Science (New York, N.Y.)》2004,305(5682):383-386

We measured the spin state of iron in magnesium silicate perovskite (Mg(0.9),Fe(0.1))SiO(3) at high pressure and found two electronic transitions occurring at 70 gigapascals and at 120 gigapascals, corresponding to partial and full electron pairing in iron, respectively. The proportion of iron in the low spin state thus grows with depth, increasing the transparency of the mantle in the infrared region, with a maximum at pressures consistent with the D" layer above the core-mantle boundary. The resulting increase in radiative thermal conductivity suggests the existence of nonconvecting layers in the lowermost mantle.  相似文献   

Biscrolling nanotube sheets and functional guests into yarns     

Lima MD  Fang S  Lepró X  Lewis C  Ovalle-Robles R  Carretero-González J  Castillo-Martínez E  Kozlov ME  Oh J  Rawat N  Haines CS  Haque MH  Aare V  Stoughton S  Zakhidov AA  Baughman RH 《Science (New York, N.Y.)》2011,331(6013):51-55

Multifunctional applications of textiles have been limited by the inability to spin important materials into yarns. Generically applicable methods are demonstrated for producing weavable yarns comprising up to 95 weight percent of otherwise unspinnable particulate or nanofiber powders that remain highly functional. Scrolled 50-nanometer-thick carbon nanotube sheets confine these powders in the galleries of irregular scroll sacks whose observed complex structures are related to twist-dependent extension of Archimedean spirals, Fermat spirals, or spiral pairs into scrolls. The strength and electronic connectivity of a small weight fraction of scrolled carbon nanotube sheet enables yarn weaving, sewing, knotting, braiding, and charge collection. This technology is used to make yarns of superconductors, lithium-ion battery materials, graphene ribbons, catalytic nanofibers for fuel cells, and titanium dioxide for photocatalysis.  相似文献