132 research outputs found
Influence of promoters on the catalytic cycles of the CO-ethene copolymerization catalyzed by [Pd(dppb)/TsO)2]
No full textPerfectly alternating CO-ethene copolymerization, catalyzed by “cationic” (diphosphine)-Pd(II) in MeOH, yields a mixuture of polyketones (PKs), CH3CH2(COCH2CH2)nCOOMe, MeO(COCH2CH2)nCOOMe and CH3CH2(COOCH2CH2)nCOCH2CH3, named KE, EE, KK, respectively. The nature of the ending groups depends on the termination/initiation steps. Termination occurs through methanolysis or protonolysis of the species Pd-CO-P or Pd-CH2CH2P (P = growing chain), which gives copolymers with at least one COOMe (E) or COCH2CH3 (K) ending group and the initiators Pd-H or Pd-OMe, respectively. Insertion of ethene or of CO into the initiators, followed by multiple alternating insertion of the monomers and by the termination/initiation steps, yields the above copolymers. The catalytic cycles leading to EE or KK are interconnected, so, ideally, they occur at the same rate and consequently the K/E ratio should be 1/1. We studied the influence of the promoters TsOH, H2O and benzoquinone (BQ) on the K/E ratio and the activity of [Pd(dppb)(TsO)2] (dppb = 1,4-bis(diphenylphosphino)butane). GC, 13C CPMAS, 13C DEMAS NMR and DSC analysis were used to measure K/E ratio, molecular weight and crystallinity. The ability of the PKs to act as a support and a stabilizer of metal nanoparticles for heterogeneous catalysts will be also shown
Evoluzione geomorfologica e tettonica quaternaria dell'Appennino centro-meridionale
No full textAtti del Convegno-Escursione "Evoluzione geomorfologica e tettonica quaternaria dell'Appennino centro-meridionale", Camerino - Salerno, 6-10 luglio 199
Selective Sorting of Senescent Cell Subpopulations Compatible with Downstream Genomics Applications
No full textEpidemiology and outcome of nosocomial candidemia in elderly patients admitted prevalently in medical wards
No full textCandidemia represents an important cause of morbidity and mortality. To-date, the highest rates of candidemia occur in elderly patients, but there are few data on such patient population. The aims of this study were to evaluate the epidemiology, treatment and outcome of candidemia in an elderly patient population
Novel Palladium catalysts supported on polyketone and on polyketone/silica: characterization and catalytic activity
No full textGenerally, metal nanoparticles catalysts are prepared in the presence of a stabilizing agents in order to prevent their agglomeration. The use of polymeric stabilizers has been widely investigated. These “quasi” homogeneous MNPs offer the advantage of high catalytic activity as the homogeneous ones, but, on the other side, they are not easily separable and recyclable as the heterogeneous ones. In order to overcome this drawback, they are generally supported on a solid inorganic carrier. On the contrary, the applications of polymers as supports have been less investigated. In particular, the use of polyketones has been almost neglected. They are high temperature melting materials, insoluble in the most common solvents. They might not only act as support, but also as stabilizer through MNP-keto groups interactions without encapsulating them with relatively strong bonds, which could inhibit catalysis as normally occurs with other stabilizers. Unfortunately, they show as drawback small surface areas and also low compatibility with hydroxylated media. A hybrid polyketones/(hydrophilic carrier) could overcome this problem. This prompted us to design a new support made of a polyketone grafted on high surface area silica. Here, we report the preparation of several Pd catalysts supported on polyketone, aerosil 380 and on polyketone-aerosil 380 with different Pd loading and polyketone/aerosil ratio, synthesized employing microwave irradiation. These systems were characterized by SEM, TEM, ICP, XPS, BET analysis and were tested in the selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde as probe reaction. The Pd/polyketone-aerosil 380 catalysts present a significantly higher activity than the Pd/polyketone and Pd/aerosil 380 systems
Bis(alkoxycarbonyl) complexes of platinum: preparation, reactivity and their role in carbonylation reactions
No full textBis(alkoxycarbonyl) complexes of platinum of the type [Pt(COOR)2L [L=1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis-(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino) butane (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppf) or 1,2-bisdiphenylphosphino)benzene (dpb); R=CH3, C6H5 or C2H5] were obtained by reaction of [PtCl2L] with carbon monoxide and alkoxides. Palladium and nichel complexes gave only carbonyl complexes of the type [M(CO)L] or [M(CO)2L]. The new complexes were characterized by chemical and spectroscopic means. The X-ray structure of [Pt(COOCH3)2(dppf).CH3OH is olso reported. The reactivity of some alkoxycarbonyl complexes was also investigated
Radon distribution as shallow evidence of buried fault geometry in the Fucino plain (Central Italy)
No full textThe Fucino plain is characterised by a network of buried and known faults activated during the Avezzano earthquake in 1915. Since radon in soil gas is used as an effective fault tracer, radon anomalies in the eastern sector of the plain has been re- interpreted according to new seismic data and new techniques of geospatial analysis to reconstruct the shallow geometry of these buried and known faults. E-W radon profiles was calculated using the radon distribution map, and the spatial distribution of radon peaks was mapped. Spatial location of the radon peaks highlights eastward sharp deviations along the NW-SE oriented Trasacco, Ortucchio Faults, as well as along the San Benedetto dei Marsi fault that borders the eastern side of the plain. These deviations can be inferred as fractured zones (e.g., relay ramps) or real transfer faults causing moving back of these structures towards the mountain
Campo di fratturazione superficiale e tettonica recente nel Bacino del Fucino (L'Aquila).
No full textTime course of cellular HIV-DNA and low-level HIV viremia in HIVâHCVÂ co-infected patients whose HCV infection had been successfully treated with directly acting antivirals
No full textHow hydrocarbons move along faults. Evidence from microstructural observations of hydrocarbon-bearing carbonate fault rocks
No full textThe microscale mechanisms of hydrocarbons movement along faults and fault zones, the potential carriers of hydrocarbons toward the productive geological traps, remain largely unknown. The majority of previous studies inferred the hydraulic behavior of faults with respect to hydrocarbon movements without providing meso and microstructural observations from faults permeated by hydrocarbons. To fill this gap, we document meso-structures together with the first fossil microstructural portraits of hydrocarbon flow and pathways along two hydrocarbon-bearing carbonate-hosted normal faults exposed in the central Apennines, Italy. In particular, we show that hydrocarbons cyclically move within tectonically active carbonate normal faults possibly during interseismic and coseismic phases of the seismic cycle. Channelized structures, injection features, and clast-cortex grains suggest the occurrence of transient and localized pulses of pressurized hydrocarbons during coseismic slip. In particular, clast-cortex grains are very similar to microstructures that develop along fault planes for slip velocities between 0.0001 and 1 m/s. Patches of hydrocarbon-bearing breccias/cataclasites with lobate and irregular boundaries, crackle breccias filled by hydrocarbons, and hydrocarbons arrested against hydrocarbon-free discrete fault planes suggest hydrocarbon flow during the interseismic phases with hydrocarbon (over)pressure dissipation after coseismic phases. Fault permeability is created during the coseismic phase and hydrocarbons penetrate the most permeable and uncemented uncohesive fault rocks within the damage zone and arrest against and/or within low-permeability and cemented fault cores. Results are consistent with previous numerical simulations on hydrocarbon movements along faults and time-lapse seismic-reflection imaging, suggesting that the movement of hydrocarbon occurs during interseismic periods within tectonically active faults and along permeable zones cyclically created by seismic activity. Results from this paper are crucial for modelling the hydraulic behavior of carbonate fault damage zone, which have progressively gained popularity as targets of hydrocarbon exploration and production and for CO2 or H storage.(C) 2022 Elsevier B.V. All rights reserved
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