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1.
An optimization problem of interactive inhomogenous flows (Steiner multicommodity network flow problem) is formulated. The problem's main characteristic is a fixed charge change when combining multicommodity communications. In this paper we propose a method for solving this problem which, in order to restrict the search on the feasible domain, reduces the original problem to a concave programming problem in the form: min {f(x)|xX} wheref:n is a concave function, andX
0
n
is a flow polytope defined by network transportation constraints. For practical large-scale problems arising from planning transportation networks on inhomogeneous surfaces defined by a digital model, a method of local optimization over a flow polytope vertex set is proposed, which is far more effective in comparison with the Gallo and Sodini method under polytope strong degeneracy conditions. 相似文献
2.
Cui C Shafir A Schmidt JA Oliver AG Arnold J 《Dalton transactions (Cambridge, England : 2003)》2005,(8):1387-1393
Reaction of SmCl3 with 1 eq of KL (L =[DippNC(Me)CHC(Me)NDipp]; Dipp = 2,6-i-Pr2C6H3) in THF afforded the dimeric samarium dichloride LSmCl2(THF)Cl2SmL (1) in high yield. Reactions of 1 with NaN(SiMe3)2, KNHAr (Ar = 2,4,6-t-Bu3C6H2), KBHEt3, and KCp*(Cp*= C5Me5) yielded various new complexes: LSmClN(SiMe3)2 (2), LSm[N(SiMe3)2]2 (3), LSmNHAr(HBEt3) (4), LSm(NHAr)2 (5), and LSmCp*Cl (6). Reaction of 1 with one eq of NaN(SiMe3)2 followed by treatment with excess AlMe3 afforded a unique bimetallic samarium tetramer Cl3L2Sm2(AlMe4)2Sm2L2Cl3 (7). Reaction of 6 with LiMe or LiCH2SiMe3 afforded LSmCp*Me (8) and LSmCp*CH2SiMe3 (9) in excellent yield. Methyl abstraction from with B(C6F5)3 in toluene yielded the cationic borate species (LSmCp*)[MeB(C6F5)3] (10). Molecular structures of 1-7 and 9 were determined by X-ray single crystal analysis. 相似文献
3.
Yichen Wu Sbastien Bouvet Susana Izquierdo Alexandr Shafir 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2643-2647
Among halogenated aromatics, iodoarenes are unique in their ability to produce the bench‐stable halogen(III) form. Earlier, such iodine(III) centers were shown to enable C?H functionalization ortho to iodine via halogen‐centered rearrangement. The broader implications of this phenomenon are explored by testing the extent of an unusual iodane‐directed para C?H benzylation, as well as by developing an efficient C?H coupling with sulfonyl‐substituted allylic silanes. Through the combination of the one‐shot nature of the coupling event and the iodine retention, multisubstituted arenes can be prepared by sequentially engaging up to three aromatic C?H sites. This type of iodine‐based iterative synthesis will serve as a tool for the formation of value‐added aromatic cores. 相似文献
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5.
Water‐Soluble Gold Nanoparticles: From Catalytic Selective Nitroarene Reduction in Water to Refractive Index Sensing
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Water‐soluble gold nanoparticles (Au NPs) stabilized by a nitrogen‐rich poly(ethylene glycol) (PEG)‐tagged substrate have been prepared by reduction of HAuCl4 with NaBH4 in water at room temperature. The morphology and size of the nanoparticles can be controlled by simply varying the gold/stabilizer ratio. The nanoparticles have been fully characterized by TEM, high‐resolution (HR) TEM, electron diffraction (ED), energy‐dispersive X‐ray spectroscopy (EDS), UV/Vis, powder XRD, and elemental analysis. The material is efficient as a recyclable catalyst for the selective reduction of nitroarenes with NaBH4 to yield the corresponding anilines in water at room temperature. Furthermore, the potential ability of the Au NPs as a refractive index sensor owing to their localized surface plasmon resonance (LSPR) effect has also been assessed. 相似文献
6.
A. S. Zaitsev L. S. Tverdokhlebova A. I. Grigar'ev G. M. Grebnova I. D. Grigor'eva P. R. Ferents A. I. Kostarev é. N. Klenov A. A. Alybakov K. S. Cholokov A. B. Chormonov A. Mukanbaev V. V. Vershinin V. B. Kashkin V. P. Kuznetsov V. M. Musonov A. I. Mitsek V. A. Feigin Z. Z. Zyman V. F. Osyka B. G. Safronov N. V. Volkov L. A. Inzhevatova R. A. Kulikovskaya O. V. Trofimov M. M. Shafir R. D. Vengrenovich A. V. Kuz'min A. D. Gorbunov V. V. Salomatov A. V. Kuz'min A. D. Gorbunov I. A. Prokhorov N. A. Dolinin 《Russian Physics Journal》1974,17(11):1628-1633
7.
Jordon-Thaden B Kreckel H Golser R Schwalm D Berg MH Buhr H Gnaser H Grieser M Heber O Lange M Novotný O Novotny S Pedersen HB Petrignani A Repnow R Rubinstein H Shafir D Wolf A Zajfman D 《Physical review letters》2011,107(19):193003
We present the results of a Coulomb explosion experiment that allows for the imaging of the rovibrational wave function of the metastable H2- ion. Our measurements confirm the predicted large internuclear separation of 6 a.u., and they show that the ion decays by autodetachment rather than by spontaneous dissociation. Imaging of the resulting H2 products reveals a large angular momentum of J = 25 ± 2, quantifying the rotation that leads to the metastability of this most fundamental molecular anion. 相似文献
8.
Wei W. Chen Ana B. Cuenca Alexandr Shafir 《Angewandte Chemie (International ed. in English)》2020,59(38):16294-16309
Hypervalent organoiodane reagents are ubiquitous in organic synthesis, both as oxidants and as electrophilic group‐transfer agents. In addition to these hallmark applications, a complementary strategy is gaining momentum that exploits the ability of λ3‐iodanes to undergo iodine‐to‐arene group transfer, for example, via iodonio‐Claisen‐type rearrangement processes. This Minireview discusses recent advances in the use of this method to access a variety of the C?H‐functionalized iodoarenes. While Section 2 is focused on the ortho C?H propargylation, allylation, and the more unusual para C?H benzylation, Section 3 is devoted to the C‐arylation of enol and phenol substrates. The accompanying discussion includes mechanistic considerations and goes into the synthetic applications of the final iodoarene cores. The Minireview concludes with further conceptual extensions of the method, including the use of non‐conventional coupling partners (for example, cyanoalkylation), improved access to λ3‐iodane building blocks, and the development of iterative approaches to polysubstituted iodoarenes. 相似文献
9.
Palladium nanoparticles supported on an organic-inorganic fluorinated hybrid material. Application to microwave-based heck reaction 总被引:1,自引:0,他引:1
Phosphine-free palladium nanoparticles were embedded in a fluorous organic-inorganic hybrid material 6b prepared by the sol-gel process. The use of Pdn.6b in the Heck coupling reaction under microwave irradiation has been investigated. Recycling studies have shown that the catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution. 相似文献
10.
Soifer H Botheron P Shafir D Diner A Raz O Bruner BD Mairesse Y Pons B Dudovich N 《Physical review letters》2010,105(14):143904
We study high-order harmonic generation in aligned molecules close to the ionization threshold. Two distinct contributions to the harmonic signal are observed, which show very different responses to molecular alignment and ellipticity of the driving field. We perform a classical electron trajectory analysis, taking into account the significant influence of the Coulomb potential on the strong-field-driven electron dynamics. The two contributions are related to primary ionization and excitation processes, offering a deeper understanding of the origin of high harmonics near the ionization threshold. This Letter shows that high-harmonic spectroscopy can be extended to the near-threshold spectral range, which is in general spectroscopically rich. 相似文献