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排序方式: 共有187条查询结果,搜索用时 31 毫秒
31.
M. Zimbone G. Litrico M. Barbera G. A. Baratta G. Foti 《Applied physics. B, Lasers and optics》2009,94(1):29-32
The defects produced in 4H-SiC epitaxial layers by irradiation with 200-keV H+ were characterized by low-temperature photoluminescence. These defects induce sharp luminescent lines, the so-called alphabet
lines. Their intensity shows an evolution under UV-laser irradiation not previously observed. By monitoring the change in
the resulting photoluminescence spectra versus time, we distinguish two original ‘families’ of peaks called PB1 and PB2. They display a different, and opposite, behaviour with laser irradiation but they are strongly correlated. In particular,
the recovering rate of the PB1 family and the growth rate of the PB2 family are the same, indicating a structural rearrangement of defects. 相似文献
32.
In the last decade, the improved performance and versatility of the mass spectrometers together with the increasing availability of gene and genomic sequence database, led the mass spectrometry to become an indispensable tool for either protein and proteome analyses in cereals. Mass spectrometric works on prolamins have rapidly evolved from the determination of the molecular masses of proteins to the proteomic approaches aimed to a large-scale protein identification and study of functional and regulatory aspects of proteins. Mass spectrometry coupled with electrophoresis, chromatographic methods, and bioinformatics tools is currently making significant contributions to a better knowledge of the composition and structure of the cereal proteins and their structure-function relationships. Results obtained using mass spectrometry, including characterization of prolamins, investigation of the gluten toxicity for coeliac patients, identification of proteins responsible of cereal allergies, determination of the protein pattern and its modification under environmental or stress effects, investigation of genetically modified varieties by proteomic approaches, are summarized here, to illustrate current trends, analytical troubles and challenges, and suggest possible future perspectives. 相似文献
33.
M. Cavallaro F. Cappuzzello D. Carbone A. Cunsolo A. Foti A. Khouaja M. R. D. Rodrigues J. S. Winfield M. Bondì 《The European Physical Journal A - Hadrons and Nuclei》2012,48(5):59
The focal plane detector of the MAGNEX large acceptance magnetic spectrometer is presented. It is based on a large low-pressure
gas-filled tracker followed by a wall of silicon detectors to stop the particles. It has been designed for the stringent requirements
from the ion optics and the foreseen use with heavy ions. The performances of the device are demonstrated using 4MeV/u oxygen beams. The results of the tests are described and discussed in view of the application of the particle identification
and trajectory reconstruction techniques to recover the kinematic properties of the reaction products. They demonstrate the
suitability of such detector in a wide range of experiments where low-energy thresholds, large-accepted solid angle, precise
momentum measurement and good particle identification are needed. 相似文献
34.
Clemente Bretti Concetta De Stefano Claudia Foti Silvio Sammartano Giuseppina Vianelli 《The Journal of chemical thermodynamics》2012,44(1):154-162
The acid–base properties of four aminophenol derivatives, namely m-aminophenol (L1), 4-amino-2-hydroxytoluene (L2), 2-amino-5-ethylphenol (L3) and 5-amino-4-chloro-o-cresol (L4), are studied by potentiometric and titration calorimetric measurements in NaCl(aq) (0 ? I ? 3 mol · kg?1) at T = 298.15 K. The dependence of the protonation constants on ionic strength is modelled by the Debye–Hückel, SIT (Specific ion Interaction Theory) and Pitzer equations. Therefore, the values of protonation constants at infinite dilution and the relative interaction coefficients are calculated. The dependence of protonation enthalpies on ionic strength is also determined. Distribution (2-methyl-1-propanol/aqueous solution) measurements allowed us to determine the Setschenow coefficients and the activity coefficients of neutral species. Experimental results show that these compounds behave in a very similar way, and common class parameters are reported, in particular for the dependence on ionic strength of both protonation constants and protonation enthalpies. 相似文献
35.
S. Cherubini E. Costanzo A. Cunsolo A. Foti M. Lattuada S. Romano C. Spitaleri A. Tumino D. Vinciguerra M. Zadro 《Zeitschrift für Physik A Hadrons and Nuclei》1997,357(3):291-296
The 12C(12C,8Beg.s.)16O reaction cross section has been measured at center-of-mass energies between 20 and 30 MeV. Intermediate width structures have been observed for the reactions leading to the ground state and two doublets of states, 6.05/6.13 MeV and 6.92/7.12 MeV, in 16O. For the 8Beg.s.+16Og.s. channel the dominant angular momenta contributing to several structures have been deduced by the analysis of the excitation functions at selected center-of-mass angles. Correlations between the structures in the 8Beg.s.+16Og.s. channel and in other inelastic scattering channels in the E c.m. = 30 MeV region are discussed. An interpretation of the resonances in terms of current structural models is given 相似文献
36.
Ahlen S Ambrosio M Antolini R Auriemma G Baker R Baldini A Barbarino GC Barish BC Battistoni G Bellotti R Bemporad C Bernardini P Bilokon H Bisi V Bloise C Bussino S Cafagna F Calicchio M Campana P Campana D Carboni M Cecchini S Cei F Chiarella V Chiera C Cobis A Cormack R Corona A Coutu S DeCataldo G Dekhissi H DeMarzo C De Vincenzi M Di Credico A Diehl E Erriquez O Favuzzi C Ficenec D Forti C Foti L Fusco P Giacomelli G Giannini G Giglietto N Giubellino P Grassi M Green P Grillo A Guarino F 《Physical review letters》1992,69(13):1860-1863
37.
Ahlen S Ambrosio M Antolini R Auriemma G Baldini A Bam BB Barbarino GC Barish BC Battistoni G Bellotti R Bemporad C Bernardini P Bilokon H Bisi V Bloise C Bussino S Cafagna F Calicchio M Campana P Campana D Carboni M Cecchini S Cei F Chiarella V Chiera C Cobis A Cormack R Corona A Coutu S DeCataldo G DeMarzo C De Vincenzi M Di Credico A Diehl E Erriquez O Favuzzi C Ficenec D Forti C Foti L Fusco P Giacomelli G Giannini G Giglietto N Giubellino P Grassi M Green P Grillo A Guarino F Gustavino C 《Physical review D: Particles and fields》1992,46(3):895-902
38.
Thermodynamic parameters for the interaction of protonated biogenic polyamines with inorganic or organic polyanions were studied potentiometrically (H(+)-glass electrode) and calorimetrically, at 25 degrees C. No background salt was used in the measurements to avoid interferences, and the formation constants and formation enthalpies were extrapolated to zero ionic strength. Species formed are ALH(r) [L=Cl(-), SO(4)(2-), HPO(4)(2-), P(2)O(7)(4-) and P(3)O(10)(5-); tartrate, malate, citrate, glutamate, 1,2,3-propanetricarboxylate, 1,2,3,4-butanetetracarboxylate], with r=1,2...(n+m-2) and r=1,2...(n+m-1) for inorganic and organic ligands, respectively (n, m=maximum degree of protonation of amine and ligand, respectively). The stability of the various species formed is a function of charges involved in the formation reaction. DeltaH(0) values are generally positive, and therefore these complexes are entropically stabilized. Results are discussed in connection with several previously reported data on similar systems. DeltaG(0) and TDeltaS(0) follow a linear trend as a function of polyammonium cation and inorganic or carboxylic anion charges. DeltaG(0) and TDeltaS(0) charge relationships are reported. In particular, mean values of DeltaG(0) and TDeltaS(0) for single interaction were calculated: DeltaG(0)=7.0 kJ mol(-1) n(-1), TDeltaS(0)=9.1 kJ mol(-1) n(-1) and DeltaG(0)=5.7 kJ mol(-1) n(-1) and TDeltaS(0)=8.7 kJ mol(-1) n(-1), for the species of inorganic and organic polyanions, respectively (n=number of possible salt bridges). A linear relationship was also found for TDeltaS(0) versus DeltaG(0), whose equation is TDeltaS(0)=-7-1.39 DeltaG(0) (with r=0.9409; r, correlation coefficient). The body of correlations found for these thermodynamic parameters shows quite good predictive value. 相似文献
39.
S. Caruso S. Foti P. Maravigna G. Montaudo 《Journal of polymer science. Part A, Polymer chemistry》1982,20(7):1685-1696
The primary fragmentation processes in the thermal decomposition of polymers were studied in detail on a series of structurally related polyureas by direct pyrolysis with a mass spectrometer. Our results indicate that polyureas I–III undergo a quantitative depolycondensation process analogous to that observed for N-monosubstituted polyurethanes. The thermal decomposition of polyureas IV–VI proceeds by intramolecular hydrogen transfer processes that occur at higher temperatures with respect to depolycondensation. Polycarboxypiperazine VI is decomposed by a single-stage decomposition mechanism that leads to fragments with amino end groups and carbon oxide. 相似文献
40.
The formation of open chain polyammonium cation-fluoride and -carbonate complexes was studied by potentiometric and calorimetric techniques at t=25 °C. Several species of HiAL (A=amine; L=F−, CO32−) are formed in both systems with a mean stability (ζ=|zanion×zcation|) and for fluoride and carbonate, respectively. The comparison with analogous systems (chloride and acetate for fluoride and hydrogenphosphate, sulfate and malonate for carbonate) showed that fluoride and carbonate form the most stable species with open chain polyammonium cations, among low molecular weight anions. The N-alkyl substitution does not play negligible role in the stability of these complexes, the species formed by substituted amines being more stable. 相似文献