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61.
Sancho-García JC Brédas JL Beljonne D Cornil J Martínez-Alvarez R Hanack M Poulsen L Gierschner J Mack HG Egelhaaf HJ Oelkrug D 《The journal of physical chemistry. B》2005,109(11):4872-4880
Various end-substituted distyrylbenzenes have been synthesized to serve as guest molecules in inclusion compounds to promote efficient energy transport along one-dimensional channels. Their optical and photophysical properties have been characterized at both experimental and theoretical levels. All molecules display a large transition dipole moment between the ground state and lowest excited state and hence a short radiative lifetime (on the order of 1-2 ns). They also exhibit a large spectral overlap between the emission and absorption spectra, which enables efficient energy transport between molecules arranged in a head-to-tail configuration in nanochannels. Hopping rates on the order of 10(12) s(-1) are calculated at a full quantum-chemical level; this is much larger than the radiative lifetimes and opens the way for energy migration over large distances. Changes in the nature of the terminal substituents are found to modulate the optical properties weakly but to impact significantly the energy transfer rates. 相似文献
62.
[reaction: see text] The room-temperature radical addition of sodium hypophosphite to terminal alkynes produces the previously unknown 1-alkyl-1,1-bis-H-phosphinates in moderate yield. The reaction is initiated by R3B and air and proceeds under mild conditions in an open container. The bissodium salts precipitate spontaneously from the reaction mixtures, thus providing a simple purification procedure and the opportunity for multigram synthesis. The 1,1-bis-H-phosphinate products are novel precursors of the biologically important 1,1-bisphosphonates. 相似文献
63.
64.
We proceed with our study of increasing self-described sequences F, beginning with 1 and defined by a functional equation
In [1] we exhibited the simple solution f (t)=Ct, for some (0,1), of the associated functional-differential equation
and we proved that provided <2/(2+d()), where
we have the asymtotic equivalence F(m)~ Cm.In the present paper we show that this last result is optimal, in the sense that the self-described sequence defined by |F–1(m)|=F(m)2, that is
for which the boundary case =2/(2+d())(=1/2) holds, does not satisfy F(m) ~ Cm. We also show that the m-th term F(m) of a sequence F for which the boundary case holds is nevertheless of asymptotic order m.Then we investigate the behaviour of self-described sequences F when lies beyond the boundary case. In [1] we established the estimates
when is the unique fixed point of a certain associated function. We were only able to prove in general that the latter holds when does not lie beyond the boundary case, however. In the present paper we prove that whenever
is the unique fixed point of this function, and in addition we obtain estimates more precise than (*). This applies for instance to the sequence defined by
that is
相似文献
65.
Kerdelhué JL Langenwalter KJ Warmuth R 《Journal of the American Chemical Society》2003,125(4):973-986
Photolysis of p-tolyldiazirine (6) in the inner phase of a hemicarcerand with four butane-1,4-dioxy linker groups (5) in C(6)D(5)CD(3) at 77 K yields the 5-methylcycloheptatetraene hemicarceplex 5 circle 3b in 41% together with innermolecular reaction products resulting from an insertion of transient p-tolylcarbene (1b) into an acetal C-H or linker C-O bond of 5 and from the addition of 1b to an aryl unit of 5. The yield of incarcerated 3b increased up to 67% if 6 is photolyzed inside a hemicarcerand with deuterated spanners and butane-1,4-dioxy linker groups (d(48)-5). Hemicarceplex 5 circle 3b is not formed if the photolysis is carried out in CDCl(3). Incarcerated 3b is stable at room temperature in the absence of oxygen and is characterized by 1D and 2D NMR spectroscopy. In the presence of oxygen, 3b reacts quantitatively to yield toluene and CO(2). Upon heating solutions of d(48)-5 circle 3b in C(6)D(5)CD(3), 3b rearranges to 1b and m-tolylcarbene (18). Both tolylcarbenes immediately react with the surrounding host. From a product analysis and the measured rate constants for the thermal decomposition of d(48)-5 circle 3b in the temperature range 70-102 degrees C, the activation parameters for the 3b to 1b and 3b to 18 rearrangements are calculated (3b to 1b: DeltaG(373)++ = 27.3 +/- 1.4 kcal/mol, DeltaH(373)++ = 26.4 +/- 1.0 kcal/mol, TDeltaS(373)++ = -0.9 +/- 1.0 kcal/mol; 3b to 18: DeltaG(373)++ = 27.8 +/- 1.4 kcal/mol, DeltaH(373)++ = 19.7 +/- 1.0 kcal/mol, TDeltaS(373)++ = 8.1 +/- 1.0 kcal/mol). These values are compared with those calculated by Geise and Hadad at the B3LYP/6-311+G** level of theory (Geise, C. M.; Hadad, C. M. J. Org. Chem. 2002, 67, 2532-2540). The slightly higher inner phase activation free energy of the 3b to 18 rearrangement is explained through steric constraints imposed by the surrounding hemicarcerand on the transition state. The enthalpy-entropy compensation observed for the 3b to 18 rearrangement is discussed and interpreted as a result of a hemicarcerand and solvent reorganization along the reaction coordinate. It is taken as indirect evidence for the intermediacy of 2-methylbicyclo[4.1.0]hepta-2,4,6-triene in the 3b to 18 rearrangement. 相似文献
66.
Guillou C Beunard JL Gras E Thal C 《Angewandte Chemie (International ed. in English)》2001,40(24):4745-4746
67.
We applied two-dimensional gel electrophoresis (2-DE) to study the repertoire of tetanus toxoid (TT)-specific antibodies produced after TT immunization in healthy humans and in severe combined immunodeficient mice xenotransplanted with either human peripheral blood leukocytes (PBLe) or with human adult tonsil (hu-ton) pieces. Specific anti-TT antibodies, as well as total immunoglobulins (Ig), were purified by affinity chromatography on TT-Sepharose or Protein G-Sepharose, respectively. 2-DE unambiguously allowed us to differentiate between the specific humoral responses produced either by humans or by the two xenochimeric mouse models. Anti-TT antibodies produced by humans were polyclonal with a superimposed oligoclonality that was donor-dependent and that did not change upon time. By contrast, immunized hu-PBLe-SCID mice exhibited an evident clonal restriction of the Ig, which increased with time after boosting. Hu-ton-SCID mice showed a clonal diversity which was intermediate between those observed in humans and in hu-PBLe-SCID mice, and which was stable over time. In addition, information was gained by 2-DE, correlating with data obtained by enzyme-linked immunosorbent assay (ELISA), on the isotype composition of the anti-TT IgM response. Altogether, our results clearly demonstrated that the clonal diversity of monospecific antibodies can be appreciated by 2-DE, and that the largest diversity was found in humans when compared to that in xenochimeric models. In addition, mice implanted with pieces of lymphoid organs had the broadest anti-TT Ig diversity, an observation supporting the use of this model for the generation of antibodies with restricted specificity. 相似文献
68.
Uncooled microbolometer detector: Recent developments at Ulis 总被引:1,自引:0,他引:1
B. Fique J.L. Tissot C. Trouilleau A. Crastes O. Legras 《Infrared Physics & Technology》2007,49(3):187-191
Uncooled infrared focal plane arrays are being developed for a wide range of thermal imaging applications. Therefore, to answer these markets, a 35 μm pixel-pitch uncooled IR detector technology has been developed enabling high performance 160 × 120 and 384 × 288 arrays production. Besides a wide-band version from uncooled 320 × 240/45 μm array has been also developed in order to address process control and more precisely industrial furnaces control. The ULIS amorphous silicon technology is well adapted to manufacture low cost detector in mass production. After some brief microbolometer technological background, we present the characterization of 35 μm pixel-pitch detector as well as the wide-band 320 × 240 infrared focal plane arrays with a pixel pitch of 45 μm. Information on the new 640 × 480 array with a pixel pitch of 25 μm is also presented. 相似文献
69.
70.
Sarah Djabarouti Pierre Duffau Fabien Xuereb Estibaliz Lazaro Carine Greib Jean-Baptiste Gordien Olivier Caubet Marie-Claude Saux Jean-François Viallard Jean-Luc Pellegrin Dominique Breilh 《Chromatographia》2009,70(5-6):939-945
Liquid chromatography coupled with mass spectrometry for the determination of total and unbound mycophenolic acid and its major metabolite in human plasma has been developed. Sample preparations were based on a fully automated solid-phase extraction process and ultrafiltration. Mass spectrometric data were acquired in a single-ion monitoring method. The analytes and nevirapine (internal standard) were well separated in an isocratic mode over 8 min. Validation study exhibited excellent linearity, with intra- and inter-day precision and accuracy of less than 12%. The assay was successfully applied to the pharmacokinetic study of mycophenolic acid in patients with autoimmune diseases. 相似文献