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391.
392.
Kontnik R Bosak T Butcher RA Brocks JJ Losick R Clardy J Pearson A 《Organic letters》2008,10(16):3551-3554
Sporulene, a C 35-terpenoid hydrocarbon with an unusual pentacyclic structure, is produced by Bacillus subtilis during sporulation. 相似文献
393.
Palumbo Piccionello A Guarcello A Calabrese A Pibiri I Pace A Buscemi S 《Organic & biomolecular chemistry》2012,10(15):3044-3052
A new family of fluorinated low molecular weight (LMW) gelators has been synthesized through SNAr substitution of 5-polyfluoroaryl-3-perfluoroheptyl-1,2,4-oxadiazoles with glycine ester. The obtained compounds give thermal and pH-sensitive hydrogels or thermo-reversible organogels in DMSO. Oxygen solubility studies showed the ability to maintain high oxygen levels in solution and in gel blend with plate counter agar (PCA). 相似文献
394.
Huhn C Ruhaak LR Mannhardt J Wuhrer M Neusüß C Deelder AM Meyer H 《Electrophoresis》2012,33(4):563-566
The combination of optical detection techniques like photometry (UV) or laser-induced fluorescence (LIF) with mass spectrometry for capillary electrophoresis offers advantages, both for later use of stand-alone CE-UV or CE-LIF systems and for combined CE-UV-MS or CE-LIF-MS analysis. Faster method development is enabled, the identification of analytes is facilitated, and it allows christian the optical detection scheme to be used for more precise quantification. However, shortcomings of current methodology and equipment hindered the broader use of such detection combinations mainly due to the long distance between the detection points (at least 20 cm). Large shifts in migration times and changes in resolution are visible between the detection traces hindering their straightforward comparison. We present here novel equipment for a robust coupling of CE-LIF-MS with the shortest possible distance between detection points (12 cm) determined by the length of the electrospray needle. In addition, we encourage the use of a normalization of detection traces using a scale of effective electrophoretic mobility to obtain the same x-scale for both detection traces. As an example, the proposed methodology is applied to a mixture of labeled as well as non-labeled N-glycans. 相似文献
395.
Xanthones with amino substituents were synthesized to diminish the photoreactivity of the xanthone chromophore with DNA, with the objective of using these molecules to study their binding dynamics with DNA. The aminoxanthones showed a strong solvatochromic effect on their singlet and triplet excited-state photophysics, where polar solvents led to a decrease of the energies for the excited states. Quenching of the triplet excited states by nitrite anions was used to determine the binding dynamics, and a residence time in the microsecond time domain was estimated for the bound 2-aminoxanthone with DNA. The quenching experiments performed showed that this methodology will not be applicable to study the binding dynamics of a wide variety of guests with DNA. 相似文献
396.
D'Anna F Frenna V Macaluso G Marullo S Morganti S Pace V Spinelli D Spisani R Tavani C 《The Journal of organic chemistry》2006,71(15):5616-5624
We have recently evidenced an interesting differential behavior in the reactivity in dioxane/water between the (Z)-2,4-dinitrophenylhydrazone (1a) and the (Z)-phenylhydrazone (1b) of 5-amino-3-benzoyl-1,2,4-oxadiazole. The former rearranges into the relevant triazole 2a only at pS+ > 4.5 while undergoing hydrolysis at high proton concentration (pS+ < 3.5); on the contrary, the latter rearranges into 2b in the whole pS+ range examined (0.1 < or = pS+ < or = 14.9). Thus, for a deeper understanding of these differences we have now collected kinetic data on the rearrangement in dioxane/water of a series of 3- or 4-substituted (Z)-phenylhydrazones (1c-l) of 5-amino-3-benzoyl-1,2,4-oxadiazole in a wide range of proton concentrations (pS+ 0.1-12.3) with the aim of gaining information about the effect of the substituent on the course of the reaction. All of the (Z)-arylhydrazones studied rearrange via three different reaction routes (specific-acid-catalyzed, uncatalyzed, and general-base-catalyzed), and the relevant results have been examined by means of free energy relationships. 相似文献
397.
Pace P. Nielsen 《Journal of Number Theory》2009,129(3):640-666
Text
Paul Erd?s, in 1950, asked whether for each positive integer N there exists a finite set of congruence classes, with distinct moduli, covering the integers, whose smallest modulus is N. In this vein, we construct a covering system of the integers with smallest modulus N=40.Video
For a video summary of this paper, please visit http://www.youtube.com/watch?v=3ev1YjVl0RY. 相似文献398.
GJ Kramer L Chen RK Fisher WW Heidbrink R Nazikian DC Pace MA Van Zeeland 《Physical review letters》2012,109(3):035003
From numerical simulation and analytical modeling it is shown that fast ions can resonate with plasma waves at fractional values of the particle drift-orbit transit frequency when the plasma wave amplitude is sufficiently large. The fractional resonances, which are caused by a nonlinear interaction between the particle orbit and the wave, give rise to an increased density of resonances in phase space which reduces the threshold for stochastic transport. The effects of the fractional resonances on spatial and energy transport are illustrated for an energetic particle geodesic acoustic mode but they apply equally well to other types of MHD activity. 相似文献
399.
Directional Regulation of Enzyme Pathways through the Control of Substrate Channeling on a DNA Origami Scaffold
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Guoliang Ke Dr. Minghui Liu Shuoxing Jiang Dr. Xiaodong Qi Yuhe Renee Yang Shaun Wootten Dr. Fei Zhang Prof. Zhi Zhu Prof. Yan Liu Prof. Chaoyong James Yang Prof. Hao Yan 《Angewandte Chemie (International ed. in English)》2016,55(26):7483-7486
Artificial multi‐enzyme systems with precise and dynamic control over the enzyme pathway activity are of great significance in bionanotechnology and synthetic biology. Herein, we exploit a spatially addressable DNA nanoplatform for the directional regulation of two enzyme pathways (G6pDH–MDH and G6pDH–LDH) through the control of NAD+ substrate channeling by specifically shifting NAD+ between the two enzyme pairs. We believe that this concept will be useful for the design of regulatory biological circuits for synthetic biology and biomedicine. 相似文献
400.
Fang J Wallikewitz BH Gao F Tu G Müller C Pace G Friend RH Huck WT 《Journal of the American Chemical Society》2011,133(4):683-685
A new zwitterionic conjugated polyelectrolyte without free counterions has been used as an electron injection material in polymer light-emitting diodes. Both the efficiency and maximum brightness were considerably improved in comparison with standard Ca cathode devices. The devices showed very fast response times, indicating that the improved performance is, in addition to hole blocking, due to dipoles at the cathode interface, which facilitate electron injection. 相似文献