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71.
Liao JH Chen CT Chou HC Cheng CC Chou PT Fang JM Slanina Z Chow TJ 《Organic letters》2002,4(18):3107-3110
[structure: see text] A push-pull conjugated molecule, 2,7-bis(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine (BPN), has been designed to bind selectively with octyl glucopyranoside (OGU). The BPN/OGU quadruple hydrogen-bonding complex adopts a rigid BPN conformation in which the proton donor (d) and acceptor (a) relays (daad) are resonantly conjugated through the ethynyl bridge, inducing pi-electron delocalization, i.e., a charge transfer effect. The excellent photophysical properties make BPN a highly sensitive probe for monitoring glucopyranoside to a detection limit of approximately 100 pM. 相似文献
72.
Silviu Polosan Tahsin J. Chow Taiju Tsuboi 《Journal of Physical Organic Chemistry》2008,21(4):315-320
Electronic states and their energies are calculated for a mixed‐ligand Ir(III) compound, (5‐chloro‐8‐hydroxyquinoline) bis(2‐phenylpyridyl) iridium (called IrQ(ppy)2‐5Cl) using time‐dependent density functional theory (TDDFT) calculations and are compared with the experimental result. A good agreement is obtained between the calculated and measured absorption spectra. The d‐πQ* molecular orbital transition gives the lowest‐energy triplet state absorption band. Its energy is estimated as 1.84 eV (671 nm), which is close to the absorption band position of 1.86 eV (666 nm) observed for IrQ(ppy)2‐5Cl doped in 4,4′‐N,N′‐dicarbazole‐biphenyl (CBP) host and of 1.88 eV (660 nm) observed for IrQ(ppy)2‐5Cl doped in polystyrene (PS). The second triplet state absorption band is caused by d‐πppy transition. Its position is calculated as 2.51 eV (494 nm). The dipole moment is estimated as 3.45 D, which is lower than the dipole moment of fac‐Ir(ppy)3. This is understood by a reduced charge transfer between Ir(III) and quinoline ligand. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
73.
This paper is concerned with the mixed sensitivity H∞ design in the most general, i.e., the four-block, case. This problem involves in a crucial manner the so-called four-block operator Γ, the norm of which is the achievable feedback tolerance. Our objective in this paper is to provide an interpretation for all singular values of Γ. These singular values are given an Adamjan-Arov-Krein interpretation in terms of the L∞ distance of an L∞ function to H∞(l). Intuitively, the singular values of Γ are the various tolerance levels that can be achieved if we allow a various number of unstable poles in the closed loop. We finally provide an upper bound on the number of singular values. 相似文献
74.
In this paper we introduce a concept of exponential dichotomy for linear skew-product semiflows (LSPS) in infinite dimensional Banach spaces, which is an extension of the classical concept of exponential dichotomy for time dependent linear differential equations in Banach spaces. We prove that the concept of exponential dichotomy used by Sacker-Sell and Magalhães in recent years is stronger than this one, but they are equivalent under suitable conditions. Using this concept we where able to find a formula for all the bounded negative continuations. After that, we characterize the stable and unstable subbundles in terms of the boundedness of the corresponding projector along (forward/backward) the LSPS and in terms of the exponential decay of the semiflow. The linear theory presented here provides a foundation for studying the nonlinear theory. Also, this concept can be used to study the existence of exponential dichotomy and the roughness property for LSPS.
75.
A detailed investigation of the conditions for formation and extraction of the thiocyanate complex of osmium by polyether-type polyurethane foam is reported. The complex which formed in solution was extracted through the “cation-chelation” mechanism and distribution coefficients of more than 104 were obtained. By using conditions which inhibit the formation of the osmium-thiocyanate complex, it was possible to leave 95% of osmium in the aqueous phase while extracting more than 95% of ruthenium into polyurethane foam. 相似文献
76.
77.
B.S.K. Chow 《Optics Communications》1974,11(3):235-237
A hologram of an object with field depth greatly exceeding the coherence length has been made with an ordinary gas laser, taking account of the reoccurence of the temporal coherence and its stability dependence on operating time. Only one object beam is used for a number of seperate exposures, so that the full output power is used. 相似文献
78.
79.
80.
Stephen A Williams Pao-Liu Chow 《Journal of Mathematical Analysis and Applications》1978,62(1):157-169
This paper proves that several initial-boundary value problems for a wide class of nonlinear reaction-diffusion equations have solutions ci(x, t), 1 ? i ? N (with ci(x, t) representing the concentration of the ith species at position x in a set at time t ? 0), which exist for all t ? 0 and are unique, smooth, nonnegative, and strictly positive for t > 0. The Volterra-Lotka predator-prey model with diffusion (to which the results above are proved to apply) is then studied in more detail. It is proved that any bounded solution of this model loses its spatial dependence and behaves like a periodic function of time alone as t → ∞. It is proved that if the spatial dimension is one or if the diffusion coefficients of the two species are equal, then all solutions are bounded. 相似文献