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81.
Conte P Mineo V Bubici S De Pasquale C Aboud F Maccotta A Planeta D Alonzo G 《Analytical and bioanalytical chemistry》2011,400(5):1443-1450
A number of pistachio oils were selected in order to test the efficacy of nuclear magnetic resonance relaxation dispersion (NMRD) technique in the evaluation of differences among oils (1) obtained from seeds subjected to different thermal desiccation processes, (2) retrieved from seeds belonging to the same cultivar grown in different geographical areas and (3) produced by using seed cultivars sampled in the same geographical region. NMRD measures relaxation rate values which are related to the dynamics of the chemical components of complex food systems. Results not only allowed to relate kinematic viscosity to relaxometry parameters but also were successful in the differentiation among the aforementioned oils. In fact, from the one hand, the larger the kinematic viscosity, the faster the rotational motions appeared as compared to the translational ones. On the other hand, relaxation rate curves (NMRD) varied according to the oxidative stresses and chemical composition of each sample. The present study showed for the first time that NMRD is a very promising technique for quick evaluations of pistachio oil quality without the need for time-consuming chemical manipulations. 相似文献
82.
Monocyclic as well as fused bicyclic systems with a nitrogen 10 atom at the bridgehead, including indolizidines and quinolizidines, can be prepared in four steps from N-Boc β-lactams. These easily prepared, highly robust, and flexible building blocks allow the incorporation of chirality and structural diversity, rendering the method feasible for diversity- as well as target-oriented synthesis. 相似文献
83.
Santoni MP Hanan GS Hasenknopf B Proust A Nastasi F Serroni S Campagna S 《Chemical communications (Cambridge, England)》2011,47(12):3586-3588
A planar bis-dipyrid-2'-yltriazine (bis-dpt) bridging ligand forms dinuclear Ru(II) complexes able to store up to eight electrons upon electrochemical reduction. 相似文献
84.
Elisa Barzagli Francesco Grazzi Francesco Civita Antonella Scherillo Antonino Pietropaolo Giulia Festa Marco Zoppi 《Applied Physics A: Materials Science & Processing》2013,113(4):1143-1150
In this work we present a systematic study of Japanese sword hand-guards (tsuba) carried out by means of non-invasive techniques using neutrons. Several tsuba from different periods, belonging to the Japanese Section of the Stibbert Museum, were analysed using an innovative approach to characterise the bulk of the samples, coupling two neutron techniques, namely Time of Flight Neutron Diffraction (ToF-ND) and Nuclear Resonance Capture Analysis (NRCA). The measurements were carried out on the same instrument: the INES beam-line at the ISIS spallation pulsed neutron source (UK). NRCA analysis allows identifying the elements present in the sample gauge volume, while neutron diffraction is exploited to quantify the phase distribution and other micro-structural parameters of the metal specimen. The results show that all samples are made of high-quality metal, either steel or copper alloy, with noticeable changes in composition and working techniques, depending on the place and time of manufacturing. 相似文献
85.
Tuszewski M. Henins I. Nastasi M. Scarborough W.K. Walter K.C. Lee D.H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(6):1653-1660
External and reentrant radio frequency inductive plasma sources are developed for plasma ion implantation and deposition processes in a 1.8 m3 vacuum vessel. Plasma densities in the range 1016 -1017 m-3 desirable for the above processes. External plasma sources could not yield the required plasma densities because of high particle losses in the transition region between the source and the main vessel. The particle losses are clarified through experiments and analysis, with and without multipole magnetic confinement. Reentrant plasma sources eliminate transmission losses and yield high plasma densities with good spatial uniformity 相似文献
86.
Takeshi Isobe Antonella Marini 《Calculus of Variations and Partial Differential Equations》1997,5(4):345-358
We prove that for generic Dirichlet boundary data there exist infinitely many topologically distinct solutions to the Dirichlet
problem for -Yang-Mills equations over . These are absolute Yang-Mills minimizers in topologically distinct connected components of the space of connections considered.
There is a special case for which only finitely many topologically distinct solutions can be found by our method. This corresponds
to the simultaneous existence of self dual and anti-self dual solutions, for the given boundary data. If the boundary data
is non-flat there exists always more than one solution. This paper generalizes to Yang-Mills fields an important result by
Brezis and Coron, who show existence of more than one minimizing harmonic map for non-constant Dirichlet data in two dimensions.
Received February 1, 1996 / Accepted March 15, 1996 相似文献
87.
This work presents the results of the ethene–CO copolymerization with in situ generated catalysts based on atropisomeric 1,4‐diphosphines and nickel(II). The influence of the reaction conditions and the NMR characterization of the copolymers are described. 相似文献
88.
The behaviour of tetracycline as an extracting agent for strontium, iodine, barium, molybdenum, technetium, zirconium, niobium, cesium, ruthenium, tellurium and uranium has been studied and the influence of the acidity of the aqueous phase upon extraction of the elements mentioned has been examined. Experiments have been made to determine whether or not the species extracted into the organic phase is the complex formed between tetracycline and the elements considered as well as to determine the time of shaking necessary so that the equilibrium between the phases is attained. As a practical application, the possibility of using the tetracycline-benzyl alcohol system for separating the fission products137Cs,140Ba,140La,141Ce,103Ru,95Zr and95Nb from each other and from uranium is presented. The same study has been made for131I,99mTc,99Mo,132Te,239Np and uranium and the steps necessary for the separation of these elements are proposed.From a thesis submitted by I. I. L. CUNHA to the Instituto de Pesquisas Energéticas e Nucleares-University of São Paulo in partial fulfillment of the requirements for a Doctor of Science's Degree. Work supported by Comissão Nacional de Energia Nuclear. 相似文献
89.
Antonella Casoli Piero Mirti Gerardo Palla 《Fresenius' Journal of Analytical Chemistry》1995,352(3-4):372-379
Proteinaceous organic materials used as ancient painting media were investigated by capillary gas chromatography (GC) and capillary gas chromatography — mass spectrometry (GC/MS). Medieval wall paintings made by the tempera technique were considered and their binding media were studied by the characterization of their main chemical components. The basic methodology is based on the determination of amino acids in samples of paint layers after hydrolysis and derivatization and on the comparison with reference proteinaceous materials. Multivariate chemometric techniques were used to facilitate the recognition of the protein source from chromatographic data. To characterize the binders further, a method was developed for the determination of fatty acids, present as minor components, by GC/MS. The use of fused-silica capillary columns coated with selected stationary phases allowed the separation of amino acid and fatty acid derivatives in a single analytical run. 相似文献
90.
This paper shows the results of underground waters last monitoring in the province of Lecce (Apulia, Southern Italy). We carried out the physical-chemical characterization of the aquifers and their classification in accordance to limit values sanctioned by Italian legislation in force, by European directives and by FAO, in order to define their quality and to establish their possible use for drinkable and irrigation purposes. The attention has been focused on salinity evaluation and underground waters contamination phenomena, due to sea-water intrusion and to the use of fertilizers. Salinity and nitrates concentrations are high in a few wells. Iron and manganese concentrations are very high for almost every sample and this is due to corrosion phenomena of artesian wells metallic structure. For a better interpretation of data, multivariate statistical analysis has been used, in order to obtain the correlation among analytical results, soils hydro-geological properties and anthropic conditions. 相似文献