5,395 research outputs found

    Amorphous metallizations for high-temperature semiconductor device applications

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    The initial results of work on a class of semiconductor metallizations which appear to hold promise as primary metallizations and diffusion barriers for high temperature device applications are presented. These metallizations consist of sputter-deposited films of high T sub g amorphous-metal alloys which (primarily because of the absence of grain boundaries) exhibit exceptionally good corrosion-resistance and low diffusion coefficients. Amorphous films of the alloys Ni-Nb, Ni-Mo, W-Si, and Mo-Si were deposited on Si, GaAs, GaP, and various insulating substrates. The films adhere extremely well to the substrates and remain amorphous during thermal cycling to at least 500 C. Rutherford backscattering and Auger electron spectroscopy measurements indicate atomic diffussivities in the 10 to the -19th power sq cm/S range at 450 C

    Low speed and angle of attack effects on sonic and near-sonic inlets

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    Tests of the Quiet, Clean Short-Haul Experimental Engine (QCSEE) were conducted to determine the effects of forward velocity and angle of attack on sonic and near-sonic inlet aerodynamic performance penalties and acoustic suppression characteristics. The tests demonstrate that translating centerbody and radial vane sonic inlets, and QCSEE high throat Mach number inlets, can be designed to operate effectively at forward speed and moderate angle of attack with good performance and noise suppression capability. The test equipment and procedures used in conducting the evaluation are described. Results of the tests are presented in tabular form

    Canola rapeseed, rapeseed, tillage.

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    Canola rapeseed. Assessment of early maturity Stage 2, lines. 89AB5, 89N38, 89EB31. Early maturity triazine resistance. 89AB6, 89N39, 89EB32. Stage 1 early maturity selections, 89AB8. Stage 2 Late maturity, 89MT43. Late maturity triazine resistance, 89MT44. Blackleg race trial, 89MT47. Interstate variety trials, 89MT45, 89ka70

    Apollo experience report: Development of guidance targeting techniques for the command module and launch vehicle

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    The development of the guidance targeting techniques for the Apollo command module and launch vehicle is discussed for four types of maneuvers: (1) translunar injection, (2) translunar midcourse, (3) lunar orbit insertion, and (4) return to earth. The development of real-time targeting programs for these maneuvers and the targeting procedures represented are discussed. The material is intended to convey historically the development of the targeting techniques required to meet the defined target objectives and to illustrate the solutions to problems encountered during that development

    Modulation of the equilibrative nucleoside transporter by inhibitors of DNA synthesis.

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    Expression of the equilibrative, S-(p-nitrobenzyl)-6-thioinosine (NBMPR)-sensitive nucleoside transporter (es), a component of the nucleoside salvage pathway, was measured during unperturbed growth and following exposure to various antimetabolites at growth-inhibitory concentrations. The probe 5-(SAENTA-x8)-fluorescein is a highly modified form of adenosine incorporating a fluorescein molecule. It binds. with high affinity and specificity to the (es) nucleoside transporter at a 1:1 stoichiometry, allowing reliable estimates of es expression by flow cytometry. Using a dual labelling technique which combined the vital DNA dye Hoechst-33342 and 5-(SAENTA-x8)-fluorescein, we found that surface expression of es approximately doubled between G1 and G2 + M phases of the cell cycle. To address the question of whether es expression could be modulated in cells exposed to drugs which inhibit de novo synthesis of nucleotides, cells were exposed to antimetabolite drugs having different modes of action. Hydroxyurea and 5-fluorouracil (5-FU), which inhibit the de novo synthesis of DNA precursors, produced increases in the expression of es. In contrast, cytosine arabinoside (ara-C) and aphidicolin, which directly inhibit DNA synthesis, produced no significant increase in es expression. Thymidine (TdR), which is an allosteric inhibitor of ribonucleotide reductase that depletes dATP, dCTP and dGTP pools while repleting the dTTP pool, had no significant effect on es expression. These data suggest that surface expression of the es nucleoside transporter is regulated by a mechanism which is sensitive to the supply of deoxynucleotides. Because 5-FU (which specifically depletes dTTP pools) causes a large increase in expression whereas TdR (which depletes all precursors except dTTP) does not, this mechanism might be particularly sensitive to dTTP pools

    Impacts of agricultural land use on biological integrity: a causal analysis

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116919/1/eap20112183128.pd

    Mirrorless all‐optical bistability in bacteriorhodopsin

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    We report direct observations of all‐optical mirrorless bistability associated with saturable absorption in three kinds of bacteriorhodopsin (BR) samples: wild‐type BR in water solution and dispersed in thin films of a polymer matrix as well as water solution of the genetically engineered mutant BRD96N. The experiments are carried out with picosecond pulses at 532 nm. The values measured for the saturation intensity are explained in terms of the relaxation of the excited M state population to the B state of the BR photocycle for the three kinds of samples studied
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