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311.
Grubor NM Liu Y Han X Armstrong DW Jankowiak R 《Journal of the American Chemical Society》2006,128(19):6409-6413
The interaction of the highly cross-reactive anti-PAH monoclonal antibody with four diastereomeric benzo[a]pyrene tetrols (BPTs) is studied by means of fluorescence line-narrowing spectroscopy. It is shown that the interaction of enantiomers of cis-BPT and trans-BPT with the antibody involves different complex geometries. These spatially different ligand-protein interactions alter the relative intensities of the excited-state vibrational frequencies of immunocomplexed molecules allowing for unambiguous spectroscopic resolution of all four enantiomeric isomers. This study represents the first example of a high-resolution, fluorescence-based spectroscopic method capable of enantiospecific differentiation. 相似文献
312.
Parkin A Cavazza C Fontecilla-Camps JC Armstrong FA 《Journal of the American Chemical Society》2006,128(51):16808-16815
Studies of the catalytic properties of the [FeFe]-hydrogenase from Desulfovibrio desulfuricans by protein film voltammetry, under a H2 atmosphere, reveal and establish a variety of interesting properties not observed or measured quantitatively with other techniques. The catalytic bias (inherent ability to oxidize hydrogen vs reduce protons) is quantified over a wide pH range: the enzyme is proficient at both H2 oxidation (from pH > 6) and H2 production (pH < 6). Hydrogen production is inhibited by H2, but the effect is much smaller than observed for [NiFe]-hydrogenases from Allochromatium vinosum or Desulfovibrio fructosovorans. Under anaerobic conditions and positive potentials, the [FeFe]-hydrogenase is oxidized to an inactive form, inert toward reaction with CO and O2, that rapidly reactivates upon one-electron reduction under 1 bar of H2. The potential dependence of this interconversion shows that the oxidized inactive form exists in two pH-interconvertible states with pK(ox) = 5.9. Studies of the CO-inhibited enzyme under H2 reveals a strong enhancement of the rate of activation by white light at -109 mV (monitoring H2 oxidation) that is absent at low potential (-540 mV, monitoring H+ reduction), thus demonstrating photolability that is dependent upon the oxidation state. 相似文献
313.
Green AE Causey PW Louie AS Armstrong AF Harrington LE Valliant JF 《Inorganic chemistry》2006,45(15):5727-5729
Microwave heating was used to prepare eta5-rhenium carborane complexes in aqueous reaction media. For carboranes bearing sterically demanding substituents, isomerization of the cage from 3,1,2 to 2,1,8 derivatives occurred concomitantly with complexation. Microwave heating was equally effective at the tracer level using technetium-99m, affording access to a new class of synthons for designing novel molecular imaging agents. 相似文献
314.
Carter C Brumbach M Donley C Hreha RD Marder SR Domercq B Yoo S Kippelen B Armstrong NR 《The journal of physical chemistry. B》2006,110(50):25191-25202
Indium-tin oxide (ITO) surfaces have been modified by chemisorption of carboxylic acid functionalized small molecules: ferrocene dicarboxylic acid (1), 3-thiophene acetic acid (2), and 6-{4-[{4'-[[4-(5-carboxy-pentyloxy)-phenyl]-(4-methoxy-phenyl)-amino]-biphenyl-4-yl}-(4-methoxy-phenyl)-amino]-phenoxy}-hexanoic acid (p-OMe)2-TPD-(C5-COOH)2) (3). Voltammetrically determined surface coverages of 1-3 increased in two stages, the first stage completing in minutes, the latter stage taking several hours. Electron-transfer rate coefficients, kS, for the probe molecule ferrocene in acetonitrile likewise increased in two stages with increasing surface coverages of 1, 2, and 3. Fourier transform infrared spectroscopy of In2O3 powders, exposed for long periods to ethanol solutions of each modifier, confirmed the formation of indium oxalate-like surface species. X-ray photoelectron spectroscopy of carboxy-terminated alkanethiol-modified gold surfaces, exposed to these same In2O3(powder)/small molecule modifier solutions, showed the capture of trace levels of indium as a result of the chemisorption of these small molecules, suggesting that slow etching of the ITO surface also occurs during the chemisorption event. Conventional aluminum quinolate/bis-triarylamine organic light-emitting diodes (OLEDs) created on ITO surfaces modified with 1, 2, and 3, with and without an overlayer of PEDOT:PSS (a poly(thiophene)/poly(stryenesulfonate) ITO modifier), showed leakage currents lowered by several orders of magnitude and an increase in OLED device efficiency. 相似文献
315.
Aniol KA Armstrong DS Averett T Benaoum H Bertin PY Burtin E Cahoon J Cates GD Chang CC Chao YC Chen JP Choi S Chudakov E Craver B Cusanno F Decowski P Deepa D Ferdi C Feuerbach RJ Finn JM Frullani S Fuoti K Garibaldi F Gilman R Glamazdin A Gorbenko V Grames JM Hansknecht J Higinbotham DW Holmes R Holmstrom T Humensky TB Ibrahim H de Jager CW Jiang X Kaufman LJ Kelleher A Kolarkar A Kowalski S Kumar KS Lambert D LaViolette P LeRose J Lhuillier D Liyanage N Margaziotis DJ Mazouz M McCormick K 《Physical review letters》2006,96(2):022003
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q2 = 0.091 GeV2 . From these data, for the first time, the strange electric form factor of the nucleon G(E)s can be isolated. The measured asymmetry of A(PV) = (6.72 +/- 0.84(stat) +/- 0.21(syst) x 10(-6) yields a value of G(E)s = -0.038 +/- 0.042(stat) +/- 0.010(syst), consistent with zero. 相似文献
316.
Wodicka LM Ciceri P Davis MI Hunt JP Floyd M Salerno S Hua XH Ford JM Armstrong RC Zarrinkar PP Treiber DK 《Chemistry & biology》2010,17(11):1241-1249
Interactions between kinases and small molecule inhibitors can be activation state dependent. A detailed understanding of inhibitor binding therefore requires characterizing interactions across multiple activation states. We have systematically explored the effects of ABL1 activation loop phosphorylation and PDGFR family autoinhibitory juxtamembrane domain docking on inhibitor binding affinity. For a diverse compound set, the affinity patterns correctly classify inhibitors as having type I or type II binding modes, and we show that juxtamembrane domain docking can have dramatic negative effects on inhibitor affinity. The results have allowed us to associate ligand-induced conformational changes observed in cocrystal structures with specific energetic costs. The approach we describe enables investigation of the complex relationship between kinase activation state and compound binding affinity and should facilitate strategic inhibitor design. 相似文献
317.
Armstrong I. Andonovic I. Kelly A.E. Bonthron S. Bebbington J. Michie C. Tombling C. Fasham S. Johnstone W. 《Lightwave Technology, Journal of》2005,23(5):1852-1859
The development of a high-performance hybrid integration platform is demonstrated using an all-optical wavelength converter based on an integrated semiconductor optical amplifier (SOA) Mach-Zehnder interferometer (MZI). The device structure, transfer functions, power penalties and regenerative properties are presented for data rates up to 10 Gb/s. 相似文献
318.
Bain M. Jin M. Loh S.H. Baine P. Armstrong B.M. Gamble H.S. McNeill D.W. 《Electron Device Letters, IEEE》2005,26(2):72-74
Silicon-on-insulator (SOI) substrates incorporating tungsten silicide ground planes (GPs) have been shown to offer the lowest reported crosstalk figure of merit for application in mixed signal integrated circuits. The inclusion of the silicide layer in the structure may lead to stress or defects in the overlying SOI layers and resultant degradation of device performance. It is therefore essential to establish the quality of the silicon on the GPSOI substrate. MOS capacitor structures have been employed in this paper to characterize these GPSOI substrates for the first time. High quality MOS capacitor characteristics have been achieved with minority carrier lifetime of /spl sim/0.8 ms. These results show that the substrate is suitable for device manufacture with no degradation in the silicon due to stress or metallic contamination resulting from the inclusion of the underlying silicide layer. 相似文献
319.
The microstructural and creep behavior of bulk 63SnPb37 and the Pb-free solder alloy Sn3.9Ag0.6Cu are reported and compared.
The Sn3.9Ag0.6Cu alloy showed much lower absolute creep rates than 63SnPb37. The size and distribution of the intermetallic
compound (IMC) coarsened with increasing creep temperature. A number of coarsened precipitates of Cu6Sn5 segregate around β-Sn grain boundaries. After creep at 80°C and 115°C. the β-Sn particles in the Sn3.9Ag0.6Cu alloy are strongly
aligned at approximately 45° to the uniaxial tension, parallel to the maximum shear-stress planes. The powerlaw-defined stress
exponent significantly increases with increasing stress in both the 63Sn37Pb and Sn3.9Ag0.6Cu alloys; therefore, the Dorn
model is unsuitable for these materials over large stress and temperature ranges. Both sets of experimental data were successfully
fit with the present power-law stress-dependent energy-barrier model and the Garofalo model. However, the application of the
present power-law stress-dependent energy model resulted in a significantly lower estimated variance as compared to the Garofalo
model. 相似文献
320.
Suppression of line voltage related distortion in current controlled grid connected inverters 总被引:5,自引:0,他引:5
Abeyasekera T. Johnson C.M. Atkinson D.J. Armstrong M. 《Power Electronics, IEEE Transactions on》2005,20(6):1393-1401
The influence of selected control strategies on the level of low-order current harmonic distortion generated by an inverter connected to a distorted grid is investigated through a combination of theoretical and experimental studies. A detailed theoretical analysis, based on the concept of harmonic impedance, establishes the suitability of inductor current feedback versus output current feedback with respect to inverter power quality. Experimental results, obtained from a purpose-built 500-W, three-level, half-bridge inverter with an L-C-L output filter, verify the efficacy of inductor current as the feedback variable, yielding an output current total harmonic distortion (THD) some 29% lower than that achieved using output current feedback. A feed-forward grid voltage disturbance rejection scheme is proposed as a means to further reduce the level of low-order current harmonic distortion. Results obtained from an inverter with inductor current feedback and optimized feed-forward disturbance rejection show a THD of just 3% at full-load, representing an improvement of some 53% on the same inverter with output current feedback and no feed-forward compensation. Significant improvements in THD were also achieved across the entire load range. It is concluded that the use of inductor current feedback and feed-forward voltage disturbance rejection represent cost-effect mechanisms for achieving improved output current quality. 相似文献