A polypeptide assembly prepared by stepwise polymerization on a self-assembled monolayer consisting of amino-alkanethiol and dialkyl disulfide oriented vertically and unidirectionally to the surface. 相似文献
[reaction: see text] Pharmacologically important diarylmethane structures have been prepared in a straightforward manner through sequentially integrated Pd-catalyzed cross-coupling reactions. (2-Pyridyl)silylmethylstannane was found to be an air-stable, storable, and versatile coupling platform in this synthetic strategy. 相似文献
Pt(II) complexes with a terpyridylazobenzene ligand (tpyAB) were newly synthesized, and their photoluminescence properties by trans-cis isomerization of the azo moiety were investigated. In these complexes, upon excitation with 366-nm light in polar solvents such as DMF, DMSO, and propylene carbonate, trans-to-cis isomerization with significant UV-vis spectral changes occurred almost completely. Cis-to-trans isomerization was observed both by irradiation with visible light and by heat. The reduction peaks due to the terpyridine and the azo group in the cyclic voltammograms of the Pt complexes were shifted in the positive direction by trans-to-cis isomerization. Emission spectral changes due to trans-cis isomerization were observed for both the tpyAB and the Pt complexes. The significant differences in the emission properties of the complex compared to tpyAB include the observation that both the excitation and emission wavelengths were shifted to lower energy, located in the visible region. Moreover, the change in emission intensity between the trans and cis forms was more significant upon excitation with UV light, because the trans form of the complexes showed absolutely no emission. Accordingly, the azobenzene-conjugated Pt(II) terpyridine complexes promise to be doubly photofunctional materials, showing complete off-on switching of emission linked to the trans-cis conformation change. 相似文献
A new reconstruction method called sampled pattern matching (SPM) was applied to the image reconstruction of an electrical
capacitance computed tomography in powder flow in a vertical pipe for petroleum refinery process. This new method is able
to achieve stable convergence without the use of an empirical value. Experiments were carried out using fluid catalytic cracking
(FCC) catalysts as powder with two air volume flow rates and four powder volume flow rates to measure the capacitance of a
pipe cross section. The SPM method is compared with conventional methods in terms of volume fraction, residual capacitance,
and correlation capacitance. Overall, the SPM method proved superior to conventional methods without any empirical value because
SPM achieves accurate reconstruction by using an objective function that is calculated as the inner product calculation between
the experimental capacitance and the reconstructed image capacitance. 相似文献
A previous theory for the electrophoresis of a cylindrical soft particle (that is, a cylindrical hard particle covered with
a layer of polyelectrolytes) [7], which makes use of the condition that the electrical force acting on the polymer segments
is balanced with a frictional force exerted by the liquid flow, is modified by replacing this condition with an alternative
and more appropriate boundary condition that pressure is continuous at the boundary between the surface layer and the surrounding
electrolyte solution. The general mobility expression thus obtained is found to reproduce all of the approximate analytic
mobility expressions derived previously.
Received: 20 July 2000/Accepted: 21 August 2000 相似文献
A numerical simulation code for three dimensional problems of near-field optics has been developed using the volume integral equation with the moment method. The object is assumed to be continuous and macroscopic dielectric and can be treated by macroscopic Maxwell#x0027;s equations. The code can treat the large-scale moment method matrix that is obtained by the discretization of the volume integral equation. The resultant matrix equation is solved by an iteration method called the generalized minimum residual method with reasonable computational cost for simple problems of near field optics. Simulation of a simplified model of a scanning near-field optical microscope has been performed and basic polarization characteristics of the system have been investigated in detail. The code is also applied to the collection-mode of a photon scanning tunneling microscope, where the incident wave is the evanescent wave, and basic relation between near-field and far field i.e., output image, is recognized. 相似文献
Nitroxide‐mediated polymerizations of styrene in microemulsion have been carried out at 125 °C using the cationic surfactant tetradecyltrimethylammonium bromide and the nitroxides 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO) and N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] nitroxide (SG1). TEMPO‐mediated polymerizations were extremely slow, with large particles (dn = 39–129 nm) and broad molecular weight distributions (MWDs). The origin of the broad MWDs was likely significant alkoxyamine decomposition and differing diffusion rates of monomer and low MW alkoxyamines (and nitroxide) between monomer‐swollen micelles and polymer particles. SG1‐mediated polymerizations proceeded at higher rates, resulting in nanoparticles (dn = 21–37 nm) and lower than for TEMPO.