Efficient multistep photoinitiated electron transfer in a molecular pentad     

Gust D  Moore TA  Moore AL  Lee SJ  Bittersmann E  Luttrull DK  Rehms AA  Degraziano JM  Ma XC  Gao F  Belford RE  Trier TT 《Science (New York, N.Y.)》1990,248(4952):199-201

A synthetic five-part molecular device has been prepared that uses a multistep electron transfer strategy similar to that of photosynthetic organisms to capture light energy and convert it to chemical potential in the form of long-lived charge separation. It consists of two covalently linked porphyrin moieties, one containing a zinc ion (P(Zn)) and the other present as the free base (P). The metailated porphyrin bears a carotenoid polyene (C) and the other a diquinone species (Q(A)-Q(B)). Excitation of the free-base porphyrin in a chloroform solution of the pentad yields an initial charge-separated state, C-P(Zn)-P(.+).-Q(A)(-)-Q(B), with a quantum yield of 0.85. Subsequent electron transfer steps lead to a final charge-separated state, C(.+)-P(Zn)-P-Q(A)-Q(B)(.-), which is formed with an overall quantum yield of 0.83 and has a lifetime of 55 microseconds. Irradiation of the free-base form of the pentad, C-P-P-Q(A)-Q(B), gives a similar charge-separated state with a lower quantum yield (0.15 in dichloromethane), although the lifetime is increased to approximately 340 microseconds. The artificial photosynthetic system preserves a significant fraction ( approximately 1.0 electron volt) of the initial excitation energy (1.9 electron volts) in the long-lived, charge-separated state.  相似文献   

REPORT OF THE ST. LOUIS MEETING     

Moore GT 《Science (New York, N.Y.)》1920,51(1306):48-50

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"THE NEW AIR WORLD"     

Moore WL  Humphreys WJ 《Science (New York, N.Y.)》1923,57(1483):639-641

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Cloned viral protein vaccine for foot-and-mouth disease: responses in cattle and swine   总被引：88，自引：0，他引：88  

D G Kleid  D Yansura  B Small  D Dowbenko  D M Moore  M J Grubman  P D McKercher  D O Morgan  B H Robertson  H L Bachrach 《Science (New York, N.Y.)》1981,214(4525):1125-1129

A DNA sequence coding for the immunogenic capsid protein VP3 of foot-and-mouth disease virus A12, prepared from the virion RNA, was ligated to a plasmid designed to express a chimeric protein from the Escherichia coli tryptophan promoter-operator system. When Escherichia coli transformed with this plasmid was grown in tryptophan-depleted media, approximately 17 percent of the total cellular protein was found to be an insoluble and stable chimeric protein. The purified chimeric protein competed equally on a molar basis with VP3 for specific antibodies to foot-and-mouth disease virus. When inoculated into six cattle and two swine, this protein elicited high levels of neutralizing antibody and protection against challenge with foot-and-mouth disease virus.  相似文献   

Band gap fluorescence from individual single-walled carbon nanotubes   总被引：1，自引：0，他引：1  

O'Connell MJ  Bachilo SM  Huffman CB  Moore VC  Strano MS  Haroz EH  Rialon KL  Boul PJ  Noon WH  Kittrell C  Ma J  Hauge RH  Weisman RB  Smalley RE 《Science (New York, N.Y.)》2002,297(5581):593-596

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.  相似文献   

Role of importin-beta in coupling Ran to downstream targets in microtubule assembly   总被引：1，自引：0，他引：1  

Wiese C  Wilde A  Moore MS  Adam SA  Merdes A  Zheng Y 《Science (New York, N.Y.)》2001,291(5504):653-656

The guanosine triphosphatase Ran stimulates assembly of microtubule asters and spindles in mitotic Xenopus egg extracts. A carboxyl-terminal region of the nuclear-mitotic apparatus protein (NuMA), a nuclear protein required for organizing mitotic spindle poles, mimics Ran's ability to induce asters. This NuMA fragment also specifically interacted with the nuclear transport factor, importin-beta. We show that importin-beta is an inhibitor of microtubule aster assembly in Xenopus egg extracts and that Ran regulates the interaction between importin-beta and NuMA. Importin-beta therefore links NuMA to regulation by Ran. This suggests that similar mechanisms regulate nuclear import during interphase and spindle assembly during mitosis.  相似文献   

MICROORGANISMS OF THE SOIL     

Moore GT 《Science (New York, N.Y.)》1912,36(932):609-616

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RELATIONS OF THE WEATHER BUREAU TO THE SCIENCE AND INDUSTRY OF THE COUNTRY     

Moore WL 《Science (New York, N.Y.)》1895,2(44):576-582

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Effects of basal debris on glacier flow   总被引：1，自引：0，他引：1  

Iverson NR  Cohen D  Hooyer TS  Fischer UH  Jackson M  Moore PL  Lappegard G  Kohler J 《Science (New York, N.Y.)》2003,301(5629):81-84

Glacier movement is resisted partially by debris, either within glaciers or under glaciers in water-saturated layers. In experiments beneath a thick, sliding glacier, ice containing 2 to 11% debris exerted shear traction of 60 to 200 kilopascals on a smooth rock bed, comparable to the total shear traction beneath glaciers and contrary to the usual assumption that debris-bed friction is negligible. Imposed pore-water pressure that was 60 to 100% of the normal stress in a subglacial debris layer reduced shear traction on the debris sufficiently to halt its deformation and cause slip of ice over the debris. Slip resistance was thus less than debris shearing resistance.  相似文献   

Ethnomathematics: native american mathematics     

Moore CG 《Science (New York, N.Y.)》1987,236(4804):1006-1007

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