An aspect of the mechanism of the hydroxyl H/ortho H scrambling in the molecular ion of benzoic acid was studied by the open-shell INDO molecular orbital method. Energies of te unrearranged structure, the planar structure in which H is attached to carbonyl oxygen and rotational conformers of the latter were studied to determine a pathway of minimum energy for rotation. The same calculations were made for salicylic acid, m-fluorobenzoic acid and p-fluorobenzoic acid. The results of these calculations agree quite well with experimental results. 相似文献
Summary: The use of electrostatically addressable templates for the directed assembly of conducting polymers and pattern transfer to another polymer substrate is demonstrated. Doped conducting polyaniline was selectively assembled on the patterned template assisted by a DC electric field. Adding an insulated silicon dioxide layer onto the surface of the silicon wafer is critical to the formation of patterned PANi rather than a PANi film. After deposition, it was demonstrated that by compression molding or solution casting methods, patterned PANi can be completely transferred to a secondary polymer substrate, such as an NBR sheet or a polyurethane film. The conductivity of PANi lines on the PU film was found to be as high as 0.87 S · cm−1. The simple one‐step assembly process for patterning conductive polymers and transfer provides a promising nanomanufacturing approach for cost‐effective and high performance flexible nanoelectronics and biosensors.
Optical image of PANi‐assembled templates with patterned gold lines connected to negative electrodes at 10 V for 1 min. 相似文献
Let B(?) be the group of homeomcrphisms of the real line having bounded support. Higman has shown that (?) is simple. Schreier conjectured in 1928 that for any simple group, the outer automorphism groiftp is solvable. But it turns out that not only is Outer(?) non-sol table, but its derived series stabilizes after one step. Thus, although the counterexample is infinite, solvability fails as it must in finite groups (rather than because the derived series descends ad infinitum). For another (new) simple group G, Outer(G) is its own derived group. A countable counterexample is also given. Most important among the new simple groups is the group of diffeomorphisms (differentiable, but not necessarily C1) of the real line having bounded support. 相似文献
An improved synthesis of (1R,3S)-3-[(tert-butoxycarbonyl)amino]cyclohexanecarboxylic acid from 3-aminobenzoic acid is described utilising milder and more selective conditions. Both a classical salt resolution and an enzymatic approach have been shown to give the desired compound in high selectivity. 相似文献
This paper describes the preparation, characterization, and application of a chemically bonded and endcapped C18 stationary phase having a doubly zirconized silica support. The stationary phase was characterized using infrared and nuclear magnetic resonance (13C and 29Si) spectroscopies, elemental analysis, and surface and thermogravimetric determinations, and evaluated chromatographically using several test mixtures, indicating acceptable efficiency, and asymmetry. The new phase was used for several different applications including the determination of the possible presence of six pesticides in orange juice, using a modified QuEChERS procedure for extraction.
Protein farnesyltransferase (FTase) catalyzes farnesylation of a variety of peptide substrates. (3)H α-secondary kinetic isotope effect (α-SKIE) measurements of two peptide substrates, CVIM and CVLS, are significantly different and have been proposed to reflect a rate-limiting S(N)2-like transition state with dissociative characteristics for CVIM, while, due to the absence of an isotope effect, CVLS was proposed to have a rate-limiting peptide conformational change. Potential of mean force quantum mechanical/molecular mechanical studies coupled with umbrella sampling techniques were performed to further probe this mechanistic dichotomy. We observe the experimentally proposed transition state (TS) for CVIM but find that CVLS has a symmetric S(N)2 TS, which is also consistent with the absence of a (3)H α-SKIE. These calculations demonstrate facile substrate-dependent alterations in the transition state structure catalyzed by FTase. 相似文献