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91.
92.
Irene Bravo-Osuna Christine Vauthier Alessandra Farabollini Gioconda Millotti Gilles Ponchel 《Journal of nanoparticle research》2008,10(8):1293-1301
Surface modified nanoparticles composed of poly(isobutylcyanoacrylate) (PIBCA) cores surrounded by a chitosan and thiolated
chitosan gel layer were prepared and characterized in previous works. The presence of such biopolymers on the nanoparticle
surface conferred those nanosystems interesting characteristics that might partially overcome the gastrointestinal enzymatic
barrier, improving the oral administration of pharmacologically active peptides. In the present work, the antiprotease behaviour
of this family of core–shell nanoparticles was in vitro tested against two model metallopeptidases present in the gastrointestinal
tract (GIT): Carboxypeptidase A -CP A- (luminal protease) and Leucine Aminopeptidase M -LAP M- (membrane protease). As previous
step, the zinc-binding capacity of these nanoparticles was evaluated. Interestingly, an improvement of both the zinc-binding
capacity and the antiprotease effect of chitosan was observed when the biopolymers (chitosan and thiolated chitosan) were
used as coating component of the core–shell nanoparticles, in comparison with their behaviour in solution, thanks to the different
biopolymer chains rearrangement. The presence of amino, hydroxyl and thiol groups on the nanoparticle surface promoted zinc
binding and hence the inhibition of the metallopeptidases analysed. On the contrary, the occurrence of a cross-linked structure
in the gel layer surrounding the PIBCA cores of thiolated formulations, due to the formation of interchain and intrachain
disulphide bonds, partially limited the inhibition of the proteases. The low accessibility of cations to the active groups
of the cross-linked polymeric shell was postulated as a possible explanation of this behaviour. Results obtained in this work
make this family of surface-modified nanocarriers promising candidates for the successfull administration of pharmacologically
active peptides and proteins by the oral route. 相似文献
93.
A Topological Criterion for the Existence of Half-Bound States 总被引:1,自引:0,他引:1
The following theorem is proved: if (M4n+1,g) is a completeRiemannian manifold and M is an oriented hypersurface partitioningM and with non-zero signature, then the spectrum of the HodgedeRhamLaplacian is [0,]. This result is obtained by a new Callias-typeindex. This new formula links half-bound harmonic forms (thatis, nearly L2 but not in L2) with the signature of . 相似文献
94.
We show that suitable upper estimates of the heat kernel are sufficient to imply the L
p
boundedness of several families of operators associated with the Schr?dinger group in various situations. This generalizes
results by Sj?strand and others in the Euclidean case, and by Alexopoulos in the case of Lie groups and Riemannian manifolds.
RID="*"
ID="*"Research partially supported by the European Commission (European TMR Network "Harmonic Analysis" 1998-2001, Contract
ERBFMRX-CT97-0159). 相似文献
95.
Brownstein SK Ding J Robertson G Roovers J Enright G 《The Journal of organic chemistry》2002,67(3):663-667
A new example of magnetic nonequivalence of chemically equivalent atoms is identified from the proton and carbon resonance spectra of 9,10-di(9,9-dioctylfluorenyl)anthracene with the aid of its conformation in the crystalline state. Molecular modeling suggests that it has a similar conformation in solution. 相似文献
96.
Claude Delmas Francis Menil Gilles Le Flem Claude Fouassier Paul Hagenmuller 《Journal of Physics and Chemistry of Solids》1978,39(1):51-53
A Mössbauer study of the dimensionality of magnetic interactions in the layer oxide LiCr0.99Fe0.01O2 shows a 2-D behaviour. 相似文献
97.
The energy balance in the fission of 234U has been investigated on the basis of experimental results from the 233U(d, pf) reaction. Taking into account the neutron evaporation we have deduced the total kinetic energy and excitation energy distributions of the primary fragments as functions of the excitation energy of the fissioning nucleus. The neutron evaporation temperatures have been adjusted so as to reproduce the average value and width of the measured kinetic energy distributions for each fragmentation. Excitation energy distributions of the fragments have been deduced. The data are discussed in the framework of the liquid-drop model with shell corrections. Evidence for energy dissipation in the fission of 234U, involving drastic changes in the scission configuration, is shown for some fragmentation modes. 相似文献
98.
Guy Solladié Christine Greck Gilles Demailly Arlette Solladié-Cavallo 《Tetrahedron letters》1982,23(48):5047-5050
It is shown that reductions of β-ketosulfoxides of identical chirality (R) at sulfur, lead to reduction products of opposite stereochemistry according to the reducing agent used. The high enantiomeric excesses obtained (80 to 100%) provide a general route to both enantiomers of methylcarbinols from the corresponding esters. 相似文献
99.
Gilles Pisier 《Acta Mathematica》1983,151(1):181-208
100.
Gilles Godefroy 《Israel Journal of Mathematics》1983,44(1):61-74
We show that ifE is a non-reflexive Banach lattice, there exists for everyn a dual of finite even order ofE which contins isometicallyl
n
/l
. We show that itE is a Banach lattice which is isometric to the dual of a Banach spaceX, then the order intervals are σ (E, X)-compact. We prove then that under various conditions, a Banach lattice which is a dual as a Banach space, is a dual as a
Banach lattice. In particular, this is true when the predual ofE is unique.
相似文献