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21.
Jean-Charles Lancelot Bertrand Letois Sylvain Rault Max Robba Maria Rogosca 《Journal of heterocyclic chemistry》1994,31(2):501-504
Cyclization of 3-(1-pyrrolyl)thiophene-2-carboxamide derivatives of methyl 3-(1-pyrrolyl)-2-thiophenecarboxylate afforded imminium salts and resulted in the formation of thieno[2,3-b]pyrrolizine derivatives. 相似文献
22.
During electrolysis of molten KF-2HF, strongly adherent fluorine bubbles are generated at the surface of carbon anode. The current was passing even if the horizontal anode was fully covered with gas film. The formation and growth of gas bubbles were studied by transient electrochemical techniques. It was observed that the fluorine bubbles do not have the spherical cap shape predicted by the classical theory. The curvature radius of the interface profile is not constant, the edge of the bubble being flat with a contact angle close to zero. The results are interpreted in the frame of a model which takes into account the predominant role of the interfacial properties. 相似文献
23.
Edmond Amouyal Bertrand Zidler Patrick Keller Alec Moradpour 《Chemical physics letters》1980,74(2):314-317
Rate constants kq for the quenching of the excited state of Ru(bipy)32+ by a series of viologen salts having different redox potential E have been determined in deaerated aqueous solutions at pH = 5 by laser flash photolysis. The kq values are found to decrease with increasing —E and to correlate with the reaction free-energy change ΔG. Such a correlation is shown to be consistent with the Rehm—Weller model for electron-transfer reactions. 相似文献
24.
Bertrand Pierre Broniatowski Michel Marcotorchino Jean-François 《Advances in Data Analysis and Classification》2022,16(4):1069-1093
Advances in Data Analysis and Classification - This paper aims at comparing two coupling approaches as basic layers for building clustering criteria, suited for modularizing and clustering very... 相似文献
25.
Gary L. Bertrand William E. Acree Jr. Thomas E. Burchfield 《Journal of solution chemistry》1983,12(5):327-346
A general equation for the estimation of thermodynamic excess properties of multicomponent systems from observed excess properties of the various binary combinations of the components has been developed, based on a simple model of the multicomponent system. This estimation takes the form $$\Delta \bar Z_{12...N}^{ex} = \sum\limits_{i = 1}^N {\sum\limits_{j > i}^N {(X_i + X_j )(f_i + f_j )(\Delta \bar Z_{ij}^{ex} )^* } } $$ in which \((\Delta \bar Z_{ij}^{ex} )^* \) is the molar excess property (enthalpy, entropy, volume, free energy, etc.), of the binary system with components at the same molar ratio as in the multicomponent system, and fi, fj are weighted mole fractions using weighting factors based on the excess properties of the binary systems. The important features of this equation are: it is applicable to a broad range of thermodynamic properties, its application to both integral and differential mixing properties is independent of the manner in which the binary mixing data is represented (Redlich-Kister equation, Wilson equation, etc.), and it provides reasonably accurate predictions ranging from quite good for simple systems of nonspecific interactions to only fair for associated solutions. This equation is recommended as a point-of-departure for mathematical representation of experimental data for multicomponent systems. 相似文献
26.
The present work discusses the grafting by electron beam irradiation of poly(ethylene oxide) (PEO) star-shaped polymers onto porous expanded polytetrafluoroethylene (EXPTFE) surfaces. The resulting materials are intended to combine the good biocompatible properties of PEO with the outstanding mechanical properties of PTFE. The star-shaped PEOs were synthesized via anionic polymerization. 3 Mev electron beam irradiation was applied to graft these PEO stars onto porous EXPTFE surfaces. The hydrophobic EXPTFE surface had to be pre-modified with N-vinylpyrrolidone. ESCA was used to quantify the amount of grafted star-shaped PEO. Unmodified EXPTFE surfaces are well known, when implanted in a body, to be rapidly covered by a layer of cells and fibrin. The EXPTFE coated with PEO were implanted in the peritoneal cavity of rats (or under the back skin). This implantation did not induce any inflammation reactions and SEM analysis had attested the absence of adsorbed cells and fibrin. The glucose diffusion properties of these membranes were studied by a lag time analysis method and compared to those of pure PEO hydrogels. As expected, glucose diffuses through the hydrogel coated membrane and diffusion is not affected by the presence of the EXPTFE membrane. 相似文献
27.
Rudzevich VL Gornitzka H Romanenko VD Bertrand G 《Chemical communications (Cambridge, England)》2001,(17):1634-1635
Addition of an excess of BunLi to the bis(borano)phosphide complex [Ar*PH(BH3)2]-Li+ 1 (Ar* = 2,4,6-tri-tert-butylphenyl) and subsequent treatment with BH3, gives the anionic complex [Ar*P(BH3)(mu-BH2)2H]-Li+ 2 instead of the expected tris(borano)phosphide dilithium, [Ar*P(BH3)3]2-2Li+ 3. 相似文献
28.
Yahan Cui Rong Deng Xiangshuai Li Xinghuo Wang Qiong Jia Emilie Bertrand Kamel Meguellati Ying-Wei Yang 《中国化学快报》1990,30(12):2291-2294
A multifunctional nanohybrid based on mesoporous silica nanoparticle and biocompatible polypeptide was fabricated for targeted and dual-responsive therapy of tumor cells. 相似文献
29.
End-labeled free-solution electrophoresis of DNA 总被引:1,自引:0,他引:1
Meagher RJ Won JI McCormick LC Nedelcu S Bertrand MM Bertram JL Drouin G Barron AE Slater GW 《Electrophoresis》2005,26(2):331-350
DNA is a free-draining polymer. This subtle but "unfortunate" property of highly charged polyelectrolytes makes it impossible to separate nucleic acids by free-flow electrophoresis. This is why one must typically use a sieving matrix, such as a gel or an entangled polymer solution, in order to obtain some electrophoretic size separation. An alternative approach consists of breaking the charge to friction balance of free-draining DNA molecules. This can be achieved by labeling the DNA with a large, uncharged molecule (essentially a hydrodynamic parachute, which we also call a drag-tag) prior to electrophoresis; the resulting methodology is called end-labeled free-solution electrophoresis (ELFSE). In this article, we review the development of ELFSE over the last decade. In particular, we examine the theoretical concepts used to predict the ultimate performance of ELFSE for single-stranded (ssDNA) sequencing, the experimental results showing that ELFSE can indeed overcome the free-draining issue raised above, and the technological advances that are needed to speed the development of competitive ELFSE-based sequencing and separation technologies. Finally, we also review the reverse process, called free-solution conjugate electrophoresis (FSCE), wherein uncharged polymers of different sizes can be analyzed using a short DNA molecule as an electrophoretic engine. 相似文献
30.
The structure of P,P-bis(diisopropylamino)-4-phenyl-1,3,2lambda(5)-diazaphosphete, 1a, has been determined by a single-crystal X-ray diffraction study (C(19)H(33)N(4)P, monoclinic system, space group P2(1), a = 9.482(1) ?, b = 11.374(3) ?, c = 9.668(2) ?, beta = 97.16(1) degrees, Z = 2). According to quantum chemical calculations at an RHF level of optimization utilizing the 6-31g(d,p) basis set, 1a has a zwitterionic structure with the negative charge delocalized on the NCN allylic fragment and the positive charge localized at the phosphorus. Heterocycle 1a reacts with water and benzaldehyde affording N-phosphoranylbenzamidine 3 (95% yield) and the expected aza-Wittig adduct 4 (85% yield), respectively. Addition of 1 equiv of methyl trifluoromethanesulfonate and of 2 equiv of BH(3).THF to 1a affords cyclic phosphonium salt 5 (94% yield) and the bis(borane) adduct 6a (90% yield), respectively. Dimethyl acetylenedicarboxylate slowly reacts with 1a giving rise to 1,3,4lambda(5)-diazaphosphinine, 9, in 70% yield. The X-ray crystal structures of products 2,3, and 6a are reported (2: C(26)H(38)N(5)P, monoclinic system, space group C2/c, a = 16.337(8) ?, b = 19.810(2) ?, c = 8.800(2) ?, beta = 117.68(2) degrees, Z = 4. 3: C(19)H(35)N(4)OP, orthorhombic system, space group P2(1)2(1)2(1), a = 9.090(1) ?, b = 12.955(2) ?, c = 17.860(3) ?, Z = 4. 6a: C(19)H(39)B(2)N(4)P, orthorhombic system, space group P2(1)2(1)2(1), a = 10.340(1) ?, b = 13.247(1) ?, c = 16.996(1) ?, Z = 4). 相似文献