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81.
André Lopez Robert Martino Armand Lattes Philippe De Loth François Crasnier 《Tetrahedron》1980,36(5):623-630
The preferred conformation of phenyl-2 aziridine involves the phenyl ring nearly bisecting the plane of the small ring (maximum conjugation). As the steric hindrance due to substituents on the aromatic ring is more substantial, the aromatic ring moves towards a perpendical plane. Good agreement between experimental (IR and NMR) and theoretical studies of the syn-anti configurational equilibrium of NH in these compounds is demonstrated. The analysis of the total electronic populations clarifies an understanding of the variation of the charge transfer small ring?aromatic cycle as a function of the aromatic nucleus. 相似文献
82.
W. Frner J. Ladik D. Hofmann M. Seel A. Godzik F. Martino 《Journal of Molecular Structure》1989,188(3-4):231-260
The influence of substitutional disorder, of random forces and of energy dissipation on solitons in alternating trans-polyacetylene using the Su-Schrieffer-Heeger Hamiltonian is discussed. Double ionization in polyene chains was also investigated. Further soliton dynamics within a full Pariser-Parr-Pople Hamiltonian for trans-polyacetylene are presented. The presence of conformational solitons in stacked systems is shown numerically in a polyformamide model system. Possible relations to DNA and carcinogenesis are briefly reviewed. 相似文献
83.
Cavallo L Cucciolito ME De Martino A Giordano F Orabona I Vitagliano A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1127-1139
Trigonal copper(I) complexes of the chiral bidentate ligand (1S,2S)-N,N'-Bis-(mesitylmethyl)-1,2-diphenyl-1,2-ethanediamine ((S,S)-1) have been prepared with hydrocarbon olefins, as well as with allylic alcohols and ethers. The stereochemistry of the complexes has been investigated by 1H NMR spectroscopy and by combined quantum mechanics and molecular mechanics (QM/MM) computational methods. The coordinated chiral nitrogen atoms can display equal (R, R) or opposite (R, S) configuration, the latter being disfavored if steric hindrance is present above and below the coordination plane. Although the complexes exist as rapidly equilibrated mixtures of stereoisomers, one of these is often dominant, and prochiral olefins are coordinated with high enantioface selection. In addition, the [(S,S)-1]-Cu+ fragment selectively recognizes the R enantiomer of secondary allylic alcohols and ethers, as confirmed by the X-ray crystal structure analysis of the adduct with (R)-1-buten-3-ol. The reasons for the observed selectivities have been elucidated, and lead to some implications which are consistent with the enantioselection observed in catalytic cyclopropanation reactions promoted by copper complexes of the same ligand. 相似文献
84.
By using the double resonance technique we have observed the infrared inactive (2ν3, E) level in methane. The experimental value of the vibrational energy (6043.8 cm?1) is in good agreement with recent calculations based on the “local mode” model. 相似文献
85.
Elena Piacenza Delia Francesca Chillura Martino Luciano Cinquanta Pellegrino Conte Paolo Lo Meo 《Magnetic resonance in chemistry : MRC》2022,60(3):369-385
A set of commercial milk and Sicilian cheeses was analysed by a combination of fast field cycling (FFC) nuclear magnetic resonance (NMR) relaxometry and chemometrics. The NMR dispersion (NMRD) curves were successfully analysed with a mathematical model applied on Parmigiano–Reggiano (PR) cheese. Regression parameters were led back to the molecular components of cheeses (water trapped in casein micelles, proteins and fats) and milk samples (water belonging to hydration shells around dispersed colloidal particles of different sizes and bulk water). The application of chemometric analysis on relaxometric data enabled differentiating milk from cheeses and revealing differences within the two sample groups of either cheeses or milk samples. Marked differences among cheeses were evidenced by statistical analysis of the sole quadrupolar peaks parameters, suggesting that these contain information on the nature of the milk used during cheese production. Hence, combination of FFC NMR and chemometrics represents a powerful tool to investigate alterations in dairy products. 相似文献
86.
Piacenza Elena Presentato Alessandro Alduina Rosa Scurria Antonino Pagliaro Mario Albanese Lorenzo Meneguzzo Francesco Ciriminna Rosaria Chillura Martino Delia F. 《Cellulose (London, England)》2022,29(10):5779-5802
Cellulose - Pectin recovered via hydrodynamic cavitation (IntegroPectin) from lemon and grapefruit agri-food waste intrinsically containing antimicrobial bioactive substances (flavonoids, phenolic... 相似文献
87.
L. Rey R. Martino L. Gambaro H. J. Thomas 《Reaction Kinetics and Catalysis Letters》1985,28(2):325-330
The oxygen equilibrium pressures from pure V2O5 and co-precipitated V2O5–TiO2 system were measured in the range of 200–450 °C. The behavior of the equilibrium pressure with changes of temperature of the samples with and without TiO2 is attributed to Ti4+ interaction with the V2O5 lattice.
V2O5 - V2O5–TiO2 200–450°C. TiO2 Ti+4 V2O5.相似文献
88.
Marianna Portaccio Daniela Durante Andrea Viggiano Silvana Di Martino Paola De Luca Daniela Di Tuoro Umberto Bencivenga Sergio Rossi Paolo Canciglia Bruno De Luca Damiano Gustavo Mita 《Electroanalysis》2007,19(17):1787-1793
Glucose microelectrodes were prepared by immobilizing glucose oxidase onto a cellulose acetate film coating a platinum wire. Hexamethylenediamine (HMDA) and Glutaraldehyde (GA) were employed as spacer and coupling agent, respectively. Sensitivities and linear response ranges were studied as a function of the relative amounts of HMDA and GA. The best sensitivity was found when HMDA and GA were 5% and 2.5% in aqueous solutions, respectively. Taking as a reference the functioning of this biosensor, the roles of HMDA and GA percentages appear to be opposed when the extension of the linear response range is considered. Indeed, an increase of one unit in HMDA percentage (from 5 to 6 %) induces an increase in the extension of the linear response range equal to that obtained with a decrease of one unit of GA percentage (from 2.5 to 1.5%). 相似文献
89.
E. D'Anna G. Leggieri A. Luches M. Martino P. Mengucci I. N. Mihailescu J. Zemek 《Progress in Surface Science》1990,35(1-4):129-142
A review is presented of the results obtained on the formation of nitride surface layers on semiconductor (Si) and metal (Ti) samples by multipulse (up to 2500) XeCl excimer laser (λ=308 nm) irradiation in N2 and NH3 atmosphere through a collaboration of Italian, Czechoslovak and Romanian laboratories. Different diagnostic techniques (optical and electron microscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger and x-ray photoelectron spectroscopy) were used to positively identify the formed compounds. Silicon nitride formation was obtained only when laser irradiation was performed in ammonia atmosphere. In contrast, when titanium samples were irradiated the nitridation process resulted very efficient in both atmospheres. The characteristics of laser synthesized nitride layers are illustrated and discussed as a function of the kind of irradiated materials, the number of subsequent laser pulses and the nature of the ambient gas. 相似文献
90.
Alessandro Chiolerio Paola Martino Paolo Allia 《Journal of magnetism and magnetic materials》2009,321(19):3099-3103
Structure, morphology and magnetic properties of thermally evaporated Co/Cr multilayers and of the solid solution obtained by isothermal treatment of the layered samples have been studied to evaluate their potential application as high-coercivity materials for hard spin injectors in spintronic devices such as magnetic tunneling junctions. The thermal treatment was performed in a partial pressure of inert gas to allow interdiffusion of Cr and Co. Structure and composition of the materials, as well as the effects of the annealing treatment, have been investigated by field emission scanning electron microscopy and energy-dispersive X-ray analysis. The magnetic configuration of these films was investigated by magnetic force microscopy. Simultaneous measurements of two mutually perpendicular magnetisation components were performed by means of a vector vibrating sample magnetometer, and showed that the in-plane coercivity can be increased by proper thermal treatment from less than 10 Oe to about 240 Oe. However, annealing may result in a loss of compositional and morphologic homogeneity of the films. 相似文献