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41.
Matthew Wallace Andre Zamith Cardoso Dr. William J. Frith Dr. Jonathan A. Iggo Dr. Dave J. Adams 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16484-16487
The magnetic‐field‐induced alignment of the fibrillar structures present in an aqueous solution of a dipeptide gelator, and the subsequent retention of this alignment upon transformation to a hydrogel upon the addition of CaCl2 or upon a reduction in solution pH is reported. Utilising the switchable nature of the magnetic field coupled with the slow diffusion of CaCl2, it is possible to precisely control the extent of anisotropy across a hydrogel, something that is generally very difficult to do using alternative methods. The approach is readily extended to other compounds that form viscous solutions at high pH. It is expected that this work will greatly expand the utility of such low‐molecular‐weight gelators (LMWG) in areas where alignment is key. 相似文献
42.
J.A. Pinston W. Mampe R. Roussille K. Schreckenbach D. Heck H.G. Börner H.R. Koch S. Andre D. Barneoud 《Nuclear Physics A》1979,321(1):25-44
Gamma and electron spectra following thermal neutron capture on 99Tc have been studied with a bent-crystal spectrometer, Ge(Li) and Si(Li) detectors and a magnetic spectrometer. Prompt and delayed γ-γ coincidences with Ge(Li) detectors have been performed. A level scheme is proposed for 100Tc comprising 21 excited states up to 640 keV. The binding energy of the last neutron in 100Tc was deduced. For most levels, spin and parity values were assigned. Two isometric transitions of respective half-lives 10.2 and 4.6 μs have been identified using the 100Mo(d, 2n)100Tc reaction with a pulsed beam of deuterons. From the comparison of the present (n, γ) study and the collaborative study of the 99Tc(d, p) reaction, several members of the multiplets , , and have been identified. 相似文献
43.
D. Andre A. Dworkin P. Figuiere A.H. Fuchs H. Szwarc 《Journal of Physics and Chemistry of Solids》1985,46(4):505-513
This calorimetric study of crystalline thiophene between 77 and 250 K reveals the existence of four phase transitions at 174.50, 170.49, 136.8 and 111.26 K, respectively. The transition II-III (170.49 K) is easily avoided during cooling, leading to metastable phases, which, in turn, exhibit their own phase transitions.These findings explain previously confused observations. The existence of stable and metastable phases was confirmed by thermally stimulated current measurements. Intermolecular Raman spectra were observed between 10 and 300 K and assigned to the observed phases. Some predictions are made concerning the low-temperature behaviour of thiophene. Tentative rules are proposed to number metastable phases relative to stable ones. 相似文献
44.
F. Baros M. Bouchy A. Bouchy J. Y. Jezequel J. C. Andre 《Reaction Kinetics and Catalysis Letters》1990,41(1):89-95
The superposition principle which is commonly used to solve the Smoluchowsky equation can be proved to be unreliable by elementary calculations applied to a particular example. But the practical kinetic consequences are small and usually hidden whithin experimental errors.
, , , , . , .相似文献
45.
In some systems, the donor of a triplet—triplet energy transfer can be sensitized in its singlet state through a singlet—singlet energy transfer (Dexter mechanism), where the donor is the acceptor of the triplet transfer itself. As a consequence an extra acceptor molecule in the triplet energy transfer is present in the vicinity of the donor, thus enhancing the efficiency of the transfer process. Experiments show clearly this effect and a diffusional model gives semi-quantitative agreement with the experimental data. 相似文献
46.
[reaction: see text] A regiospecific and convergent route the lipophilic antifolate piritrexim (PTX) is described in which a key step is a Pd(0)-catalyzed cross-coupling reaction between 2-amino-3-cyano-4-methyl-5-bromopyridine and 2,5-dimethoxybenzylzinc chloride to form 2-amino-4-methyl-5-(2,5-dimethoxybenzyl)nicotinonitrile. To complete the synthesis, the amino group is replaced by a more reactive bromine atom via nonaqueous diazotization with tert-butyl nitrite, and the resultant bromo nitrile is cyclized with guanidine. 相似文献
47.
Wenjun Tang Dr. Andrew G. Capacci Xudong Wei Dr. Wenjie Li Dr. Andre White Dr. Nitinchandra D. Patel Jolaine Savoie Joe J. Gao Sonia Rodriguez Dr. Bo Qu Dr. Nizar Haddad Dr. Bruce Z. Lu Dr. Dhileepkumar Krishnamurthy Dr. Nathan K. Yee Dr. Chris H. Senanayake Dr. 《Angewandte Chemie (International ed. in English)》2010,49(34):5879-5883
48.
Park SJ Gesquiere AJ Yu J Barbara PF 《Journal of the American Chemical Society》2004,126(13):4116-4117
The complex, coupled mechanisms of charge transfer and oxidative damage in organic electronic devices (such as organic light-emitting diodes (OLED), solar cells, etc.) have been elucidated by a new technique that combines single-molecule spectroscopy with charge injection from a metal electrode. The experiments employed a sandwich device architecture (Au/TPD/MEH-PPV:PMMA/SiO2/ITO), essentially a modified OLED with a charge-blocking layer (SiO2) to suppress charge injection at the ITO electrode. The fluorescence (photoluminescence) of isolated MEH-PPV conjugated polymer molecules imbedded in the device was observed to exhibit diverse time- and electrical bias-dependent effects. These include: (i) fluorescence quenching due to interactions between MEH-PPV and holes in the TPD hole-transport layer; (ii) fluorescence quenching, or "photobleaching", due to chemical defects at MEH-PPV generated by photooxidation; and (iii) a novel process, reductive "repair" of the oxidative chemical defects by externally injected carriers. These results demonstrate a very different mechanism for photobleaching of organic conjugated materials than is generally assumed to operate and, furthermore, suggest an intimate relationship among photobleaching, charge transport, and persistent photoconductivity in organic materials. 相似文献
49.
Abstract The knowledge of water exchange reaction mechanism in aqueous solutions of Gd3+ polyaminocarboxylates is important for the understanding of the relatively slow water exchange rates measured for these complexes. Variable ressure measurements show a change of mechanism from associatively activated on [Gd(H2O)8]3+ and [Gd(PDTA)(H2O2)2]? to probably limiting dissociative on the MRI contrast agents [Gd(DOTA)(H2O)]?, [Gd(DTPA)(H2O)]2? and [Gd(DTPA-BMA)(H2O)]. 相似文献
50.
Site‐Specific Isotope‐Labeling of Inosine Phosphoramidites and NMR Analysis of an Inosine‐Containing RNA Duplex 下载免费PDF全文