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1.
Federica Valentini Giulia Brufani Benedetta Di Erasmo Luigi Vaccaro 《Current Opinion in Green and Sustainable Chemistry》2022
The great challenge for modern research is to define the most efficient tools to make more sustainable the industrial production and manufacturing. Among the different aspects that require attention the replacement of toxic and/or non-renewable solvents it is certainly playing a crucial role. Dealing with widely used dipolar aprotic solvents, among the different alternatives proposed in the literature γ-valerolactone (GVL) plays a pivotal role covering different application area. In this contribution, the benefits derived from the use of GVL as a circular, safe, biomass-derived reaction medium are highlighted covering most recent publications (2021). The presentation has been divided into three major sections: (i) biomass valorization, (ii) materials synthesis, manufacturing and recycle and (iii) new synthetic methodologies. 相似文献
2.
Cataldo Agostinelli 《Meccanica》1968,3(2):57-68
Summary This paper deals first with the equations of motion of a conductive, homogeneous and isotropic elastic body subjected not only to externally applied mass forces and surface forces, but also to a uniform magnetic field, in which an induced magnetic field is generated.On the assumption that the electrical conductivity is infinite, the problem of motion is reduced to the consideration of a single differential vector equation in which the displacement of a point in the elastic body is the only unknown. The conditions that must be satisfied at the surface are then considered.Using the generalised formula of Kirchhoff, formulas expressing the Cartesian components of the displacement, the cubic dilatation and the rotation components are established by means of the so-called fundamental elements.
Sommario In questo lavoro si considerano innanzitutto le equazioni del moto di un corpo elastico omogeneo isotropo, elettricamente conduttore, soggetto, oltre che a forze di massa e superficiali generiche, anche a un campo magnetico uniforme, e nel quale si genera un campo magnetico indotto.Nell'ipotesi di conducibilità elettrica infinita il problema di moto si riduce alla considerazione di una sola equazione differenziale vettoriale indefinita in cui è incognito il solo spostamento di un punto del corpo elastico. Vengono stabilite successivamente le condizioni che devono essere verificate in superficie.Utilizzando poi la formula generalizzata di Kirchhoff, si stabiliscono delle formule di rappresentazione delle componenti cartesiane dello spostamento, della dilatazione cubica e delle componenti della rotazione, per mezzo dei cosidetti elementi fondamentali.相似文献
3.
Synthesis of voiced sounds using low-dimensional models of the vocal cords and time-varying subglottal pressure 总被引:1,自引:0,他引:1
Edson Cataldo Fabiana R. Leta Jorge Lucero Lucas Nicolato 《Mechanics Research Communications》2006,33(2):250-260
The vocal cords play an important role on voice production. Air coming from the lungs is forced through the narrow space between the two vocal cords that are set in motion in a frequency that is governed by the tension of the attached muscles. The motion of the vocal cords changes the type of flow, that comes from the lungs, to pulses of air, and as the flow passes through the oral and nasal cavities, it is amplified and further modified until it is radiated from the mouth. This complex process can be modeled by a system of integral-differential equations. This paper considers two mechanical models previously used for explaining the dynamics of the vocal cords. It shows that the level of naturalness of the sound generated by these models is rather poor, and it proposes temporal variations of the parameters of the models to increase such level. Examples of synthetic vowels and diphthongs are given to assess the models. In general, the results show that, although the system of voice production is complex, we can achieve satisfactory results with relatively simple low-dimensional models, by suitable temporal variations of the aerodynamic parameters. 相似文献
4.
Franco Cataldo Pietro Ragni Susana Iglesias-Groth Arturo Manchado 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):573-580
The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide
decay in a timescale of 1.05 × 109 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids
was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of
the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy.
Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best
radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after
radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all
cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 × 109 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 × 109 years. 相似文献
5.
Dr. Luka Ðorđević Cataldo Valentini Dr. Nicola Demitri Cécile Mézière Magali Allain Prof. Dr. Marc Sallé Dr. Andrea Folli Prof. Dr. Damien Murphy Samuel Mañas-Valero Prof. Dr. Eugenio Coronado Prof. Dr. Davide Bonifazi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):4135-4143
Herein we report an efficient synthesis to prepare O-doped nanographenes derived from the π-extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed-valence (MV) complexes were grown in which the organic salts organize into face-to-face π-stacks, a favorable solid-state arrangement for organic electronics. Variable-temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar π-stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that π-extension of heteroatom-doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities. 相似文献
6.
Carbon nitride films by RF plasma assisted PLD: Spectroscopic and electronic analysis 总被引:1,自引:0,他引:1
E. Cappelli S. OrlandoD.M. Trucchi A. BellucciV. Valentini A. MezziS. Kaciulis 《Applied Surface Science》2011,257(12):5175-5180
Carbon nitride (CNx) thin films have been grown on Si 〈1 0 0〉 by 193 nm ArF ns pulsed laser ablation of a pure graphite target in a low pressure atmosphere of a RF generated N2 plasma and compared with samples grown by PLD in pure nitrogen atmosphere. Composition, structure and bonding of the deposited materials have been evaluated by X-ray photoelectron spectroscopy (XPS), and Raman scattering. Significant chemical and micro-structural changes have been registered, associated to different nitrogen incorporation in the two types of films analyzed. The intensity of the reactive activated species is, indeed, increased by the presence of the bias confined RF plasma, as compared to the bare nitrogen atmosphere, thus resulting in a different nitrogen uptake in the growing films. The process has been also investigated by some preliminary optical emission studies of the carbon plume expanding in the nitrogen atmosphere. Optical emission spectroscopy reveals the presence of many excited species like C+ ions, C atoms, C2, N2; and CN radicals, and N2+ molecular ions, whose relative intensity appears to be increased in the presence of the RF plasma. The films were also characterised for electrical properties by the “four-probe-test method” determining sheet resistivity and correlating surface conductivity with chemical composition. 相似文献
7.
Austin Nevin Daniela Comelli Iacopo Osticioli Lucia Toniolo Gianluca Valentini Rinaldo Cubeddu 《Analytical and bioanalytical chemistry》2009,395(7):2139-2149
The assessment of the influence of natural and artificial ageing on the spectrofluorescence of triterpenoid varnishes dammar
and mastic is the focus of this work. Both Fourier transform infrared (FTIR) microscopy using attenuated total reflectance
and Raman spectroscopy have been employed for complementary molecular analysis of samples. Synchronous fluorescence spectroscopy,
excitation emission spectroscopy, and statistical analysis of data have been used to monitor changes in the optical properties
of varnish samples. Assessment of naturally and artificially aged samples using excitation emission spectroscopy suggests
that extensive exposure to visible light does not lead to easily appreciable differences in the fluorescence of mastic and
dammar; cluster analysis has been used to assess changes, which occur with artificial ageing under visible light, indicating
that differences in the fluorescence spectra of aged triterpenoids may be insufficient for their discrimination. The results
highlight significant differences between the initial fluorescence of films of dammar and mastic and the fluorescence, which
develops with ageing and oxidation, and specific markers, which change with ageing in FTIR and Raman spectra, have been identified. 相似文献
8.
We numerically study properties of the dynamics of vortices in nonrotating Bose-Einstein condensates in the Thomas-Fermi regime. On the one hand, we compute the vortex energy as a function of its position and we predict, using the expression of the Magnus force, the vortex precession velocity. On the other hand, we calculate the temporal evolution of the vortex-state and test the accuracy of the previous prediction. We also investigate the validity of analytical formulae of this velocity involving the healing length. In addition, we analyze the velocity field and the angular momentum and we compare them to available analytical expressions. 相似文献
9.
Grammatico Cataldo 《偏微分方程通讯》2013,38(9-10):1475-1491
We prove that two linked circles in R3 evolving by curvature develop three dimensional fattening at finite time. The same result holds for a suitable class of planar closed linked curves. 相似文献
10.
Franco Cataldo Giancarlo Angelini Donatella Capitani Marco Gobbino Ornella Ursini Fabrizio Forlini 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):839-849
This paper is dedicated to the memory of our friend and colleague Annalaura Segre. The chemical structure of a series of β (-)-pinene polymers (PBP) obtained by radiation-induced polymerization, free radical initiation, cationic polymerization over a Friedel-Craft catalyst and by coordinative polymerization over a Ziegler-Natta catalyst has been fully elucidated by 1H and 13C-NMR spectroscopy. 2D NMR techniques have been applied in order to assign all the NMR resonances to the structures of the PBP investigated. The NMR spectra show that the most regular PBP structure is obtained by radiation-induced polymerization followed by the free radical initiated polymerization. The most defective structure has been observed in the case of PBP prepared by cationic mechanism over a Friedel-Crafts catalyst. The discussion accounts for different types of defects and cross-links present in the PBPs investigated whose fundamental structure is based on the p-menthene repeating unit. NMR self-diffusion measurements have been performed to evaluate the molecular weight of all the PBP investigated. The highest molecular weight (2600 Dalton) was found in the case of PBP prepared by Ziegler-Natta catalyst, while the lowest molecular weight was found in the case of PBP prepared by radiation-induced polymerization (about 1000 Dalton). 相似文献