排序方式: 共有91条查询结果,搜索用时 15 毫秒
31.
Dibutyltin-3-hydroxyflavone bromide [Bu2SnBr-(of)] is a fluorescent inhibitor (excitation max, 395 nm; emission max., 450 nm) of mitochondrial F1F0–ATPase which does not inhibit F1–ATPase. Bu2SnBr(of) binding to mitochondria and submitochondrial particles results in a 10-fold fluorescence enhancement which correlates with the amount of F1F0–ATPase in the inner membrane. Enhancement is not affected by respiratory-chain substrates, ATP, uncoupling agents, ionophores or respiratory-chain inhibitors. It is reversed by tributyltin chloride (Bu3SnCl), indicating competition for a common triorganotin-binding site on the F0 segment of F1F0–ATPase. Enhancement is not reversed by dialkyltins, monoalkyltins, tributyl-lead acetate, efrapeptin or oligomycin. Bu2SnBr(of) is thus a new class of fluorescent probe of the F0 segment of F1F0–ATPase which titrates F0. 相似文献
32.
Chitosan membrane with glutathione reductase and sulfhydryl oxidase (SOX) was subsequently integrated onto the surface of spectrographic graphite rods for obtaining a glutathione biosensor. The working principle was based on the monitoring of O2 consumption that correlates the concentration of glutathione during the enzymatic reaction. A linear relationship between sensor response and concentration was obtained between 0.5 and 2.0 mM for oxidized glutathione (GSSG), and 0.2–1.0 mM for reduced glutathione (GSH) in the presence of 2 μM nicotinamide adenine dinucleotide phosphate (NADPH) under the optimum working conditions. Also, reduced/oxidized glutathione were separated by HPLC and utility of bienzymatic system was investigated as an electrochemical detector for the analysis of these compounds. All data were given as a comparison of two systems: biosensor and diode array detector (DAD). 相似文献
33.
Lu G Usta H Risko C Wang L Facchetti A Ratner MA Marks TJ 《Journal of the American Chemical Society》2008,130(24):7670-7685
Realizing p-channel semiconducting polymers with good hole mobility, solution processibility, and air stability is an important step forward in the chemical manipulation of charge transport in polymeric solids and in the development of low-cost printed electronics. We report here the synthesis and full characterization of the dithienosilole- and dibenzosilole-based homopolymers, poly(4,4-di-n-hexyldithienosilole) (TS6) and poly(9,9-di-n-octyldibenzosilole) (BS8), and their mono- and bithiophene copolymers, poly(4,4-di-n-hexyldithienosilole-alt-(bi)thiophene) (TS6T1, TS6T2) and poly(9,9-di-n-octyldibenzosilole-alt-(bi)thiophene) (BS8T1, BS8T2), and examine in detail the consequences of introducing dithienosilole and dibenzosilole cores into a thiophene polymer backbone. We demonstrate air-stable thin-film transistors (TFTs) fabricated under ambient conditions having hole mobilities as large as 0.08 cm(2)/V x s, low turn-on voltages, and current on/off ratios > 10(6). Additionally, unencapsulated TFTs fabricated under ambient conditions are air-stable, an important advance over regioregular poly(3-hexylthiophene) (P3HT)-based devices. Density functional theory calculations provide detailed insight into the polymer physicochemical and charge transport characteristics. A direct correlation between the hole injection barrier and both TFT turn-on voltage and TFT polymer hole mobility is identified and discussed, in combination with thin-film morphological characteristics, to explain the observed OTFT performance trends. 相似文献
34.
We present here the synthesis, characterization, and field-effect performance of a novel n-channel semiconducting molecule TIFDMT and of the corresponding thiophene-based copolymer P-IFDMT4 based on the indenofluorenebis(dicyanovinylene) core. TIFDMT-based field-effect transistors fabricated by spin-coating exhibit high electron mobilities of 0.10-0.16 cm2/V s in air, low turn-on voltages (0 to +5 V), and high on/off ratios of 10(7)-10(8). These devices also exhibit excellent air stability over a prolonged time of storage in ambient conditions. P-IFDMT4-based devices exhibit the first example of an air-stable ambipolar polymer processable from solution 相似文献
35.
Gulay Algul Yusuf Ceylan Hacer Yumurtaci Aydogmus Ayhan Usta Biray Asik 《辐射效应与固体损伤》2016,171(5-6):451-460
1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969?kGy per hour at room temperature for 24, 48 and 72?h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400?K. ESR spectra were recorded from the samples irradiated for 48 and 72?h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-+?NH and R=?CC2H2. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably. 相似文献
36.
We demonstrate that a polymer confined to a narrow channel migrates towards the center when driven by an external force parallel to the channel walls. This migration results from asymmetric hydrodynamic interactions between polymer segments and the confining walls. A weak pressure-driven flow, applied in the same direction as the external force, enhances the migration. However, when the pressure gradient and the external force act in opposite directions the polymer can migrate towards the boundaries. Nevertheless, for sufficiently strong forces the polymer always migrates towards the center. A dumbbell kinetic theory explains these results qualitatively. A comparison of our results with experimental measurements on DNA suggests that hydrodynamic interactions in polyelectrolytes are only partially screened. We propose new experiments and analysis to investigate the extent of the screening in polyelectrolyte solutions. 相似文献
37.
Artner LM Merkel L Bohlke N Beceren-Braun F Weise C Dernedde J Budisa N Hackenberger CP 《Chemical communications (Cambridge, England)》2012,48(4):522-524
A combination of classical site-directed mutagenesis, genetic code engineering and bioorthogonal reactions delivered a chemically modified barstar protein with one or four carbohydrates installed at specific residues. These protein conjugates were employed in multivalent binding studies, which support the use of proteins as structurally defined scaffolds for the presentation of multivalent ligands. 相似文献
38.
39.
Huang H Chen Z Ponce Ortiz R Newman C Usta H Lou S Youn J Noh YY Baeg KJ Chen LX Facchetti A Marks T 《Journal of the American Chemical Society》2012,134(26):10966-10973
Understanding the relationship between molecular/macromolecular architecture and organic thin film transistor (TFT) performance is essential for realizing next-generation high-performance organic electronics. In this regard, planar π-conjugated, electron-neutral (i.e., neither highly electron-rich nor highly electron-deficient) building blocks represent a major goal for polymeric semiconductors, however their realization presents synthetic challenges. Here we report that an easily accessible (minimal synthetic steps), electron-neutral thienyl-vinylene (TVT)-based building block having weak intramolecular S···O "conformational locks" affords a new class of stable, structurally planar, solution-processable, high-mobility, molecular, and macromolecular semiconductors. The attraction of merging the weak TVT electron richness with supramolecular planarization is evident in the DFT-computed electronic structures, favorable MO energetics, X-ray diffraction-derived molecular structures, experimental lattice coehesion metrics, and excellent TFT performance. TVT-based polymer TFTs exhibit stable carrier mobilities in air as high as 0.5 and 0.05 cm(2)/V·s (n- and p-type, respectively). All-TVT polymer-based complementary inverter circuitry exhibiting high voltage gains (~50) and ring oscillator circuitry with high f(osc)(~1.25 kHz) is readily fabricated from these materials by simple inkjet printing. 相似文献
40.
Ayhan Usta Mehmet Birey Nursen Sari Aliye Altundas Dilek Nartop 《Journal of Physical Organic Chemistry》2012,25(4):309-313
Ethyl 2‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carboxylate [C11H15NO2S] was synthesized by the Gewald method. Its single crystals were grown from an alcohol/ethyl acetate solution at 15 °C and characterized using IR and 1H‐NMR. These single crystals were irradiated for 72 h at 298 K by a 60Co gamma source with a dose speed of 0.864 kGy/h. After irradiation, electron spin resonance (ESR) measurements were carried out to study radiation‐induced radicals in the temperature range from 120 to 450 K. Additionally, for the single crystal, ESR angular dependencies were measured in the xy, xz and yz planes of the substance. This irradiated single crystal was analyzed based on the ESR spectra. Analysis of the spectra revealed that the radical was formed by a C–H bond fission at the carbon end of the substance. It was also observed that the color of the sample changed after irradiation. The hyperfine and g parameters were determined from the experimental spectra. It was inferred from these results that the hyperfine parameters and g value exhibited anisotropic behavior. The average values of these parameters were calculated as follows: g = 2.0088, AH1=H2 = 20.70 G, AH3=H4 = 10.80 G, AHa = 4.59 G, AHb = 3.24 G and, AN = 6.10 G. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献