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71.
Marina Mancini 《Annali dell'Universita di Ferrara》1999,45(1):163-175
In this paper we study the embeddings of smallest degree of a generic curveC of genusg as a projectively normal curve.
Sunto In questo articolo studiamo le immersioni di grado minimo di una generica curvaC di genereg come curva proiettivamente normale.相似文献
72.
Ines Mancini Graziano Guella Helmut Zibrowius Francesco Pietra 《Helvetica chimica acta》2000,83(7):1561-1575
Eunicellane diterpenes with a C(7)=C(16) (Δ7,16; see 17 – 19 ), (Z)‐C(7)=C(8) ((7Z)Δ7,8; see 20 – 23 ), and (Z)‐C(6)=C(7) ((6Z)Δ6,7; see 10 ) bond, an uncommon feature in the case of extensive functionalization at the cyclohexane ring and the latter exhibiting uncommon configurations, were isolated from the gorgonian Eunicella cavolinii from Marseille (Figs. 5 and 2). The gorgonian Eunicella singularis (=Eunicella stricta) from the same area gave (7Z)Δ7,8, Δ7,16, and (6E)Δ6,7 analogs 24 , 25 , and 13 , respectively (Fig. 5 and Scheme). The (6E)Δ6,7 moiety of 13 – characterized by a slow 180° conformational flipping (Fig. 3) that results in broadening of NMR signals – makes the macrocycle highly strained. This may explain the spontaneous conversion of 13 to the 6‐methoxy‐7‐hydroxy derivative 14 in the presence of MeOH at −20° in the dark (Scheme). The isomeric, deacylated analogue 10 showed only little broadening of NMR signals and proved stable, in accordance with the less strained nature of this compound (Fig. 4). 相似文献
73.
Donato Monti Pietro Tagliatesta Giovanna Mancini Tristano Boschi 《Angewandte Chemie (International ed. in English)》1998,37(8):1131-1133
The porphyrin–surfactant interaction determines the activity of the title catalysts. Amphiphilic porphyrin derivatives (e.g. 1 with M=MnCl, R=CH2CH2(OCH2CH2)2OH) are easy to prepare and can be included in micellar phases. 相似文献
74.
Ines Mancini Graziano Guella Helmut Zibrowius Dominique Laurent Francesco Pietra 《Helvetica chimica acta》1999,82(10):1681-1689
Massileunicellins A ( 7 ), B ( 9 ), and C ( 11 ) – which show a novel type of a second epoxy bridge in eunicellane diterpenes – were isolated from the gorgonian Eunicella cavoliniii collected near Marseille. Structural assignments are based on NMR and MS data of these compounds and of their ketal derivatives 8 , 10 , and 12 . Negligible activity of the massileunicellins on L1210 and KB tumor cell lines, and similar results for related known compounds, cast doubt on high cytotoxicity reported for the latter by other authors. 相似文献
75.
Daiana T. Mancini Eugenio F. Souza Melissa S. Caetano Teodorico C. Ramalho 《Magnetic resonance in chemistry : MRC》2014,52(4):129-137
The phenylbenzothiazole compounds show antitumor properties and are highly selective. In this paper, the 99Tc chemical shifts based on the (99mTc)(CO)3(NNO) complex conjugated to the antitumor agent 2‐(4′‐aminophenyl)benzothiazole are reported. Thermal and solvent effects were studied computationally by quantum‐chemical methods, using the density functional theory (DFT) (DFT level BPW91/aug‐cc‐pVTZ for the Tc and BPW91/IGLO‐II for the other atoms) to compute the NMR parameters for the complex. We have calculated the 99Tc NMR chemical shifts of the complex in gas phase and solution using different solvation models (polarizable continuum model and explicit solvation). To evaluate the thermal effect, molecular dynamics simulations were carried, using the atom‐centered density matrix propagation method at the DFT level (BP86/LanL2dz). The results highlight that the 99Tc NMR spectroscopy can be a promising technique for structural investigation of biomolecules, at the molecular level, in different environments. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
76.
77.
Rossi B Verrocchio P Viliani G Scarduelli G Guella G Mancini I 《The Journal of chemical physics》2006,125(4):44511
Vibrational properties of inclusion complexes with cyclodextrins are studied by means of Raman spectroscopy and numerical simulation. In particular, Raman spectra of the nonsteroidal, anti-inflammatory drug indomethacin undergo notable changes in the energy range between 1600 and 1700 cm(-1) when inclusion complexes with cyclodextrins are formed. By using both ab initio quantum chemical calculations and molecular dynamics, we studied how to relate such changes to the geometry of the inclusion process, disentangling single-molecule effects, from changes in the solid state structure or dimerization processes. 相似文献
78.
Säily VM Ryhänen SJ Lankinen H Luciani P Mancini G Parry MJ Kinnunen PK 《Langmuir : the ACS journal of surfaces and colloids》2006,22(3):956-962
The properties of a novel disulfide-bond-containing gemini surfactant bis[N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide] disulfide (DSP) were studied using a Langmuir balance, supported monolayers, differential scanning calorimetry, giant vesicles, and LUVs. In 150 mM NaCl the cmc for DSP was 7.5 microM whereas that of the monomer N,N-dimethyl-N-hexadecyl-N-(2-mercaptoethyl)ammonium bromide (MSP) was 12.1 microM. Both surfactants exhibited single endotherms upon DSC, with peak temperatures Tm at 21.7 and 20.1 degrees C for DSP and MSP, respectively. The endotherm for MSP was significantly broader indicating less cooperative melting. Both in monolayers and in vesicles reductive cleavage of the disulfide bond of DSP could be obtained by glutathione (GSH). For Langmuir films of DSP the addition of GSH into the subphase led to a decrease in surface pressure pi as well as surface dipole potential psi. Although the cleavage by GSH was significantly slower in the presence of a charge saturating concentration of DNA, it did not prevent the reaction. The resulting monomers detached from supported monolayers, leading to loss of affinity of the surface for DNA. Disruption of giant vesicles containing DSP within approximately 30 s following a local injection of GSH was observed, revealing membrane destabilization. 相似文献
79.
Bello C Bombelli C Borocci S di Profio P Mancini G 《Langmuir : the ACS journal of surfaces and colloids》2006,22(22):9333-9338
The preparation and characterization of three stereoisomeric cationic gemini surfactants, 2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonio)butane dibromide, are described. The aggregation properties have been studied by fluorescence, electrical conductivity, and quasi-elastic light scattering. A conformational study of the surfactant headgroups has been performed by molecular mechanics calculations to investigate the effect of the stereogenic centers on the surfactant molecular shape and therefore on the different organizations of the monomers in the aggregates. Results show that the stereochemistry of the spacer strongly influences the aggregation behavior of the diasteromeric gemini in water. 相似文献
80.
G. Vidal M.S. Baptista H. Mancini 《The European physical journal. Special topics》2014,223(8):1601-1610
We present a stream cipher based on a chaotic dynamical system. Using a chaotic trajectory sampled under certain rules in order to avoid any attempt to reconstruct the original one, we create a binary pseudo-random keystream that can only be exactly reproduced by someone that has fully knowledge of the communication system parameters formed by a transmitter and a receiver, sharing the same initial conditions. The plaintext is XOR’ed with the keystream creating the ciphertext, the encrypted message. This keystream passes the NIST’s randomness test and has been implemented in a videoconference App for smartphones, in order to show the fast and light nature of the proposed encryption system. 相似文献