Analytically unramified one-dimensional semilocal rings and their value semigroups

AbstractIn a one-dimensional local ring R with finite integral closure each nonzerodivisor has a value in Nd, where d is the number of maximal ideals in the integral closure. The set of values constitutes a semigroup, the value semigroup of R. We investigate the connection between the value semigroup and the ring. There is a particularly close connection for some classes of rings, e.g. Gorenstein rings, Arf rings, and rings of small multiplicity. In many respects, the Arf rings and the Gorenstein rings turn out to be opposite extremes. We give applications to overrings, intersection numbers, and multiplicity sequences in the blow-up sequences studied by Lipman

The effect of butanol isomers on the formation of carbon particulate matter in fuel-rich premixed ethylene flames

Abstract The effect of the butanol isomers on carbon particulate matter formation was studied by substituting up to 20% of the total carbon of ethylene, fed to premixed flames with different equivalence ratios, with the four butanol isomers. Soot and condensed-phase nanostructures were tracked by means of particle size distribution (PSD) measurements and laser induced emission spectroscopy, namely fluorescence and incandescence. Butanol isomers, especially t-butanol, significantly reduced the total amount and the size of the soot particles, whereas a negligible effect was detected on condensed-phase nanostructures. PSDs were measured along with the aromaticity and functionalities of the carbon particulate matter thermophoretically sampled in the highest equivalence ratio condition. No significant differences were found among the different butanol isomers neither in the soot aggregate size, as measured by size exclusion chromatography, nor in the aromaticity, as evaluated by Raman and UV–vis spectroscopy, of the particulate matter. Conversely, FTIR analysis showed that carbon particulate matter produced from 1-butanol and t-butanol-doped flames contained larger amounts of oxygen in form of C = O, C–O–C and OH functionalities. However, most of the differences in the oxygen functionalities disappeared after dichloromethane (DCM) treatment, suggesting that these oxygenated moieties belong to the condensed-phase nanostructures, soluble in DCM, rather than to soot particles

Wo3 and ionic liquids: A synergic pair for pollutant gas sensing and desulfurization

This review deals with the notable results obtained by the synergy between ionic liquids (ILs) and WO3 in the field of pollutant gas sensing and sulfur removal pretreatment of fuels. Starting from the known characteristics of tungsten trioxide as catalytic material, many authors have proposed the use of ionic liquids in order to both direct WO3 production towards controllable nanostructures (nanorods, nanospheres, etc.) and to modify the metal oxide structure (incorporating ILs) in order to increase the gas adsorption ability and, thus, the catalytic efficiency. Moreover, ionic liquids are able to highly disperse WO3 in composites, thus enhancing the contact surface and the catalytic ability of WO3 in both hydrodesulfurization (HDS) and oxidative desulfurization (ODS) of liquid fuels. In particular, the use of ILs in composite synthesis can direct the hydrogenation process (HDS) towards sulfur compounds rather than towards olefins, thus preserving the octane number of the fuel while highly reducing the sulfur content and, thus, the possibility of air pollution with sulfur oxides. A similar performance enhancement was obtained in ODS, where the high dispersion of WO3 (due to the use of ILs during the synthesis) allows for noteworthy results at very low temperatures (50◦ C)

Effectiveness of Flax-TRM composites under traction

The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguarding of the Built Cultural Heritage. Textile Reinforced Matrix (TRM) composites are the most widely investigated strengthening systems for ancient masonry structures, thanks to their high compatibility level with the material substrates in terms of fire resistance, chemical/physical aspects, reversibility property, little impact on dimensions, stiffness and weight. Nevertheless, in the last years, the growing concern on sustainability increased the interest in products with low environmental impact, for promoting circular economy approaches in the design of the structural interventions. In particular, efforts have been done to replace the most common composites with materials less harmful to the environment, such as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of experimental tests conducted by the authors on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar. The mechanical characterization tests aimed at detecting the tensile behaviour of the natural TRM system compared to the results available in the literature on different vegetable-fibre composites and TRMs made with natural basalt fibres. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered a hint to further research aimed at improving their mechanical strength and stiffness

Particle formation in premixed ethylene-benzene flames: An experimental and modeling study

Abstract In this work soot formation was studied in laminar premixed flames of binary ethylene-benzene mixtures varying throughout the composition range from pure ethylene to pure benzene keeping constant the equivalence ratio (φ = 2) and obtaining a very similar maximum temperature (Tmax around 1750 K). In such way, it was possible to study for the first time the effect of binary aliphatic-aromatic fuel mixtures composition on the sooting behavior in comparable combustion conditions. In-situ optical techniques (laser induced incandescence and fluorescence) and ex-situ particle size distribution (PSD) measured downstream of the flame front, as well as modeling by means of a multi-sectional method, were applied. PSD profiles showed that particles with sizes less than 10 nm decrease as benzene percentage in the feed mixture increases, disappearing for benzene percentages above 30%. Conversely, large aggregates grow towards sizes larger than 100 nm when benzene concentration is increased. A non-linear effect of the benzene content in the binary fuel mixture on soot particle concentration was observed by laser induced incandescence, and confirmed by the multi-sectional model. In particular soot formation was found to increase more than linear up to 50% then leveled off to reincrease linearly from 80% to 100%. On the contrary, particles smaller than 10 nm at the end of the flame rapidly decreased for benzene percentages larger than 30%. From reaction rate analysis, the formation of gas-phase polycyclic aromatic hydrocarbons (PAH) and high-molecular mass aromatics precursors was found to be significantly large already for fuel mixtures featured by low benzene amounts (from 10 up to 40–50%). The enhanced aromatic precursor formation, combined with the abundance of acetylene mainly coming from the dehydrogenation of ethylene as predominant component of the binary fuel mixture, appeared to be responsible for the non-linear effect of ethylene-benzene composition on particle formation, particularly significant up to 40–50% of benzene. This finding has a considerable importance as regards the exploitation of highly-aromatic fuels as well as to foresee the soot emission for effect of the aromatic presence in natural and synthetic fuels used in practical combustion systems

DBS-Based Eutectogels: Organized Vessels to Perform the Michael Addition Reaction**

Supramolecular eutectogels were obtained from the gelation of 1,3 : 2,4-dibenzylidene-D-sorbitol (DBS) in cholinium chloride-based deep eutectic solvents (DES), differing for the nature of the hydrogen bond donor. Ethylene glycol, diethylene glycol, triethylene glycol, glycerol and urea were tested. Soft materials were fully characterized, determining critical gelation concentration, gel-sol transition temperatures and mechanical properties. Furthermore, to have information about the organization of the gelator in the tridimensional network, resonance light scattering, circular dichroism and microscopy investigations were performed. Eutectogels were used as organized “vessels” to perform the L-proline catalyzed Michael addition reaction. The probe reaction was carried out in gel phase and in DES solution. Data collected shed light on the effect that gel microenvironment exerts on the outcome of the reaction. In general, gel phases allowed having comparable or even better results than the ones collected in DES solution, with better results obtained in soft materials with the highest organization, as accounted for by the presence of larger aggregates and the occurrence of stronger intermolecular interactions. In turn, this accounts also for the effect of substrates structure that indicates that better yields could be obtained in the presence of more flexible nucleophile and dienones, having more extended π-surface

A kinetic study of the basic hydrolysis of 2-phenylethyl nitrite in the presence of borate buffer and β-cyclodextrin

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Polarization and high resolution parametric spectral analisys applied to the seismic signals recorded on the Marsili submarine volcano

The Ocean Bottom Seismometer with Hydrophone deployed by the Gibilmanna OBS Lab (CNT-INGV) from the 12th to the 21st July 2006 on the flat top of the Marsili submarine volcano (790m of depth) recorded more than 1000 seismic events. By comparing them with the ones recorded in other volcanic areas and described in literature (Wassermann, 2002; McNutt, 2002; Díaz et al., 2007), we grouped these events in three categories: 817 VTB (Volcanic-Tectonic type B) events, 159 HF (High Frequency) events and 53 SDE’s (Short Duration Event). Small-magnitude VTB swarms, with frequency band between 2 and 6 Hz and mean time length of about 30 seconds, were almost all recorded in the first 7 days, while in the last 2 days, OBS recorded HF events with frequency band over 40 Hz and few minutes of length. Signals with similar frequency and time domain features are associated, to hydrothermal activity (Ohminato, 2006). The SDE waveform, characterized by a monochromatic signal with a slowly decaying envelope, is generated by oscillations of a resonant body excited by magmatic or hydrothermal activity (Chouet, 1996). We applied, to all the signals dataset, polarization and high resolution parametric spectral analysis. This kind of study allowed to mark the VTB events as multi P-phase events with shallow sources placed in a narrow azimuthal window as regards the OBS/H position. The seismogenetic volume is probably located in the North-East sector of the Marsili building. The high resolution parametric spectral analysis of the SDE signals allowed to find with high accuracy their dominant complex frequencies (!=f+ig). Plotting them in the complex frequencies plane we identified two distinct clusters with middle complex frequencies f=7.8s^−1, g=-0.35s^−1 and f=7.5s^−1, g=-0.47s^−1 respectively. These two clusters are probably linked two different seismogenetic volumes

Aspetti dell'alimentazione di alcune specie di selaci del Canale di Sicilia

I Selaci occupano gli ultimi livelli delle reti trofiche marine: si tratta infatti di carnivori che, spesso, predano risorse utili anche all'uomo. Numerose specie demersali (squali, razze e torpedini) si alimentano, infatti, con organismi di interesse commerciale come Aristeidi, Peneidi, Cefalopodi e Pesci ossei. Le abitudini alimentari dei Selaci demersali del Canale di Sicilia sono quasi completamente sc onosciute; esistono in letteratura i lavori di Capapé relativi alle acque tunisine, che si limitano ad una descrizione puramente qualitativa delle diete ma che hanno tuttavia evidenziato preferenze verso Crostacei Decapodi, Cefalopodi e Teleostei. Lo studio dei contenuti stomacali dei Selaci può fornire dunque elementi utili alla comprensione delle reti trofiche demersali, all'indagine sull'esistenza di competizione tra le diverse specie e allo studio dell'interferenza con prede di valore commerciale

Hall Anomaly and Vortex-Lattice Melting in Superconducting Single Crystal YBa2Cu3O7-d

Sub-nanovolt resolution longitudinal and Hall voltages are measured in an ultra pure YBa2Cu3O7-d single crystal. The Hall anomaly and the first-order vortex-lattice melting transition are observed simultaneously. Changes in the dynamic behavior of the vortex solid and liquid are correlated with features of the Hall conductivity sxy. With the magnetic field oriented at an angle from the twin-boundaries, the Hall conductivity sharply decreases toward large negative values at the vortex-lattice melting transition.Comment: 6 pages, 2 figures included, Postscript, to appear in Phys. Rev. Let