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51.
In the past years extensive studies have been conducted on porphyrin-type photosensitizers because of their photosensitive activity. With regard to their interaction with many important macromolecules such as nucleic acids, proteins and lipids, porphyrin-type photosensitizers are capable of damaging numerous cells. They damage DNA via oxidation of four bases, especially guanine and cytosine pairs[1], damage protein by oxidation of (at least) two amino acids——cysteine and tryptophan residues… 相似文献
52.
Bulgakov R. G. Akhmadieva R. G. Musavirova A. S. Golikova M. T. 《Russian Chemical Bulletin》2001,50(4):731-733
Chemiluminescence (max = 790 nm) in the oxidation of fulleride Na2C60 by the (NH4)2Ce(NO3)6 complex in THF was found. The 3C60* triplet of fullerene formed in the transfer of an electron from the intermediate C60
– anion to CeIV was suggested to be the chemiluminescence emitter. 相似文献
53.
Jeffrey Hakim 《Journal of Number Theory》2003,100(2):251-269
If G is a totally disconnected group and H is a closed subgroup then, according to the Gelfand-Kazhdan Lemma, if the double coset space H?G/H is preserved by an antiautomorphism of G of order two then (G,H) must be a Gelfand pair in the sense that HomH(π,1) has dimension at most one for each irreducible, admissible representation π of G. Under certain rather general restrictions, we show that if the symmetry property holds only for almost all double cosets, then (G,H) is a supercuspidal Gelfand pair in the sense that for all irreducible, supercuspidal representations π of G. There exist examples of supercuspidal Gelfand pairs which are not Gelfand pairs. 相似文献
54.
Let be a spherical pair and assume that is a connected compact simple Lie group and a closed subgroup of . We prove in this paper that the homogeneous manifold is weakly symmetric with respect to and possibly an additional fixed isometry . It follows that M. Krämer's classification list of such spherical pairs also becomes a classification list of compact weakly symmetric spaces. In fact, our proof involves a case-by-case study of the isotropy representations of all spherical pairs on Krämer's list.
55.
Kyung Moon Jung Kyung Hwan Kim Jung‐Il Jin Min Ju Cho Dong Hoon Choi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(22):7517-7533
New deep‐red light‐emitting phosphorescent dendrimers with hole‐transporting carbazole dendrons were synthesized by reacting tris(2‐benzo[b]thiophen‐2‐yl‐pyridyl) iridium (III) complex with carbazolyl dendrons by DCC‐catalyzed esterification. The resulting first‐, second‐, and third‐generation dendrimers were found to be highly efficient as solution‐processable emitting materials and for use in host‐free electrophosphorescent light‐emitting diodes. We fabricated a host‐free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/Alq3 (40 nm)/LiF (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m2 at 383.4 mA/cm2 (12 V) for 15 , 1302 cd/m2 at 321.3 mA/cm2 (14 V) for 16 , and 422 cd/m2 at 94.4 mA/cm2 (18 V) for 17 . The third‐generation dendrimer, 17 (ηext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light‐harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep‐red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable materials for dendrimer light‐emitting diode (DLED) applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7517–7533, 2008 相似文献
56.
Yunhua Xu Rong Guan Jiaxing Jiang Wei Yang Hongyu Zhen Junbiao Peng Yong Cao 《Journal of polymer science. Part A, Polymer chemistry》2008,46(2):453-463
A new strategy to realize efficient white‐light emission from a binary fluorene‐based copolymer (PF‐Phq) with the fluorene segment as a blue emitter and the iridium complex, 9‐iridium(III)bis(2‐(2‐phenyl‐quinoline‐N,C3′)(11,13‐tetradecanedionate))‐3,6‐carbazole (Phq), as a red emitter has been proposed and demonstrated. The photo‐ and electroluminescence properties of the PF‐Phq copolymers were investigated. White‐light emission with two bands of blue and red was achieved from the binary copolymers. The efficiency increased with increasing concentration of iridium complex, which resulted from its efficient phosphorescence emission and the weak phosphorescent quenching due to its lower triplet energy level than that of polyfluorene. In comparison with the binary copolymer, the efficiency and color purity of the ternary copolymers (PF‐Phq‐BT) were improved by introducing fluorescent green benzothiadiazole (BT) unit into polyfluorene backbone. This was ascribed to the exciton confinement of the benzothiadiazole unit, which allowed efficient singlet energy transfer from fluorene segment to BT unit and avoided the triplet quenching resulted from the higher triplet energy levels of phosphorescent green emitters than that of polyfluorene. The phosphorescence quenching is a key factor in the design of white light‐emitting polyfluorene with triplet emitter. It is shown that using singlet green and triplet red emitters is an efficient approach to reduce and even avoid the phosphorescence quenching in the fluorene‐based copolymers. The strategy to incorporate singlet green emitter to polyfluorene backbone and to attach triplet red species to the side chain is promising for white polymer light‐emitting diodes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 453–463, 2008 相似文献
57.
Significant influence of sample preparation on thermal decomposition of polyolefin-technological oil mixtures was proved during
tests. Samples of polymer-oil mixtures were prepared with two methods: reducing size and components mixing and soaking in
temperature 170°C. Soaking causes decreasing thermal stability of the charge. This fact manifests itself in decreasing of
thermal decomposition temperature in laboratory scale, as well as in change of characteristic decomposition temperatures during
thermogravimetric analyses. Data analysis was performed with the use of classic method based on Arrhenius kinetic equation
and three-parameter model. The influence of sample composition and preparation method on values of three-parameter equation
coefficients was observed. 相似文献
58.
Time-resolved moderated luminescence of aromatic ketones (benzophenone, aceptophenone) in the presence of neutral and reactive
hydrogeneous foreign gases (ethylene, pentane, triethylamine) is investigated. It is shown that the addition of hydrogeneous
foreign gases leads to strong quenching of the triplet molecules of aromatic ketones. Effectivenesses of such bimolecular
processes as the collision detachment of a hydrogen atom and establishment of vibrational and thermal equilibrium are compared.
It is concluded that the vibrational degrees of freedom of the acceptors, the aromatic ketones, are inactive in the photochemical
process of collision detachment of a hydrogen atom that takes place after the establishment of vibrational equilibrium.
Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072,
Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 73–77, January–February, 1999. 相似文献
59.
Dr. Gongping Duan Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(42):12642-12649
A series of tetracyanoruthenate(II) with chelating pyridyl N‐heterocyclic carbene ligands (NHC‐py) was synthesized and characterized. Their photophysical and electrochemical properties as well as the photochromic behavior of their dithienylethene‐containing complexes were studied. Photocyclization was found to take place upon irradiation into the metal‐to‐ligand charge transfer (MLCT) absorption bands of these complexes, and evidence is provided to support the triplet‐sensitizing reaction pathway. 相似文献
60.