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121.
Emmanuel Lacte Bndicte Delouvri Louis Fensterbank Max Malacria 《Angewandte Chemie (International ed. in English)》1998,37(15):2116-2118
Alkylidene-substituted cyclopentane derivatives are formed in high enantiomeric purity by the reaction shown below. A highly diastereoselective radical cyclization is followed by elimination of a β-sulfinyl radical. Interestingly, the addition of the Lewis acid methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD) totally reverses the stereochemical outcome of the reaction. E=CO2Me. 相似文献
122.
Bagineni Prasad Mara Doimo Mns Andrasson Valentin LHte Erik Chorell Sjoerd Wanrooij 《Chemical science》2022,13(8):2347
G-quadruplex (G4) DNA structures are implicated in central biological processes and are considered promising therapeutic targets because of their links to human diseases such as cancer. However, functional details of how, when, and why G4 DNA structures form in vivo are largely missing leaving a knowledge gap that requires tailored chemical biology studies in relevant live-cell model systems. Towards this end, we developed a synthetic platform to generate complementary chemical probes centered around one of the most effective and selective G4 stabilizing compounds, Phen-DC3. We used a structure-based design and substantial synthetic devlopments to equip Phen-DC3 with an amine in a position that does not interfere with G4 interactions. We next used this reactive handle to conjugate a BODIPY fluorophore to Phen-DC3. This generated a fluorescent derivative with retained G4 selectivity, G4 stabilization, and cellular effect that revealed the localization and function of Phen-DC3 in human cells. To increase cellular uptake, a second chemical probe with a conjugated cell-penetrating peptide was prepared using the same amine-substituted Phen-DC3 derivative. The cell-penetrating peptide conjugation, while retaining G4 selectivity and stabilization, increased nuclear localization and cellular effects, showcasing the potential of this method to modulate and direct cellular uptake e.g. as delivery vehicles. The applied approach to generate multiple tailored biochemical tools based on the same core structure can thus be used to advance the studies of G4 biology to uncover molecular details and therapeutic approaches.The development of an approach to generate multiple tailored biochemical tools based on the same core structure, Phen-DC3, to advance studies of G4 biology to uncover molecular details and therapeutic approaches. 相似文献
123.
C. Viollette E. Aubin L. Alla L'Hôte und M. A. Scovell 《Fresenius' Journal of Analytical Chemistry》1889,28(1):624-625
Ohne Zusammenfassung 相似文献
125.
C. Udrişte 《Journal of Optimization Theory and Applications》2008,139(1):141-157
Control problems for multitime first-order PDE arise in many different contexts and ways. The obstruction of complete integrability
conditions (path independent curvilinear integrals) has determined the mathematicians to study such problems only in the discrete
context, though thus they loose the geometrical character which is proper to the continuous approach.
In this paper, we study controllability, observability and bang-bang properties of multitime completely integrable autonomous
linear PDE systems, overcoming the existent mathematical prejudices regarding the importance of a multitime evolution of m-flow type. Our geometrical arguments show that each basic theorem has a correspondent in the case of a single-time linear
controlled ODE system.
The main results include controllability criteria, equivalence between controllability of a PDE system and observability of
the dual PDE system, geometry of the control set, extremality and multitime bang-bang principle. All of these show that the
passing from controlled single-time evolution (1-flow) to the controlled multitime evolution (m-flow) is not trivial. Changing the geometrical language, the case of nonholonomic evolution can be recovered easily from
our theory. 相似文献
126.
127.
We present exact results for several universal parameters of the tricritical O(n) model in two dimensions. The results apply to the range −2⩽n⩽3/2, and include the central charge and three scaling dimensions, associated with temperature, magnetic field and the introduction
of an interface. Since these results are based on an extrapolation of known relations between the O(n) and the Potts model, they cannot be considered as rigorous. For this reason, we perform an accurate numerical analysis of
the central charge and the critical exponents. This analysis, which is based on transfer-matrix calculations on the honeycomb
lattice, is in a full and precise agreement with the theoretical predictions.
相似文献
128.
The influence of drying temperature on the properties of latex films was investigated by gravimetry, turbidimetry (i.e., analysis of transmission spectra and interference), atomic force microscopy and measurement of water vapor permeability. Several pitfalls in the determination of water content of dried films that absorb water after being submerged in it have been proposed, such as fading boundaries, remaining water after drying and change of particle sizes. At moderately higher temperatures film formation is improved. This improvement follows from the formation of smoother film surfaces (AFM), lower water vapor permeabilities and smaller values for delta lambda(min). On the other hand, defects as cracks and channels also are created, especially at high temperatures. It appears, however, that these channels do not run from the one surface of a film to the other. 相似文献
129.
130.
B.?Smeets Email author R.C.M.?Bosch P.?van der Straten E.?te Sligte R.E.?Scholten H.C.W.?Beijerinck K.A.H.?van Leeuwen 《Applied physics. B, Lasers and optics》2003,76(8):815-819
Polarization spectroscopy of an Fe-Ar hollow cathode discharge cell was used to lock a frequency-doubled Ti:sapphire laser to the 372-nm5D45F5 transition of 56Fe. The discharge cell produced a density of 1018 m-3 ground-state 56Fe atoms at a temperature of 650 K, this density being comparable to a conventional oven at 1500 K. Saturated absorption spectroscopy and two schemes of polarization spectroscopy were compared with respect to signal-to-background ratio and the effect of velocity-changing collisions. The laser was locked within 0.2 MHz for hours by feedback of the dispersive polarization spectroscopy signal. PACS 33.55.Ad; 42.62.Fi; 52.25.Ya 相似文献