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排序方式: 共有108条查询结果,搜索用时 15 毫秒
41.
Giulio Franzese Dimitrios Milios Maurizio Filippone Pietro Michiardi 《Entropy (Basel, Switzerland)》2021,23(11)
Stochastic gradient sg-based algorithms for Markov chain Monte Carlo sampling (sgmcmc) tackle large-scale Bayesian modeling problems by operating on mini-batches and injecting noise on sgsteps. The sampling properties of these algorithms are determined by user choices, such as the covariance of the injected noise and the learning rate, and by problem-specific factors, such as assumptions on the loss landscape and the covariance of sg noise. However, current sgmcmc algorithms applied to popular complex models such as Deep Nets cannot simultaneously satisfy the assumptions on loss landscapes and on the behavior of the covariance of the sg noise, while operating with the practical requirement of non-vanishing learning rates. In this work we propose a novel practical method, which makes the sg noise isotropic, using a fixed learning rate that we determine analytically. Extensive experimental validations indicate that our proposal is competitive with the state of the art on sgmcmc. 相似文献
42.
The adsorption, photoreduction and chemical activity of oxygen molecules on the (1 0 0) anatase surface have been investigated here together with the effects that surface oxygen vacancies (VO) can have on these O2-related processes. We use an original approach by treating molecules on the TiO2 surface like surface defects in the same framework successfully used for defects in semiconductors. The achieved results: (i) give the first theoretical evidence of an acceptor behaviour of an adsorbed O2 molecule, which is at the origin of its photoreduction; (ii) show that the VO donor character is strongly affected by the interaction with O2; and (iii) suggest that the release of radicals as well as the formation of O2-related radicals may be favoured by photogenerated electrons in presence of surface VO’s. 相似文献
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44.
The linear rheology of PP-TiO2 composites was investigated as a function of the filler particle size. Small amounts (ϕ = 4.5%) of micron and nano-sized TiO2 spherical particles were added to the polymer by melt compounding. In spite of the low particle volume fractions and the weak polymer-filler interactions, relevant changes have been observed in the linear viscoelastic behaviour of the nanostructured formulations. Microstructural analyses performed through electron microscopy have shown a good degree of dispersion of micron-sized particles. Conversely, the presence of a relevant number of TiO2 nanoparticle clusters has been detected for the nanocomposite. The structure of these aggregates seems to be strongly responsible for the rheological behaviour of these last materials in comparison with microstructured ones. Relevant similarities between the viscoelastic properties of nanocomposite and the flow feature of many soft glassy materials have been noticed, and a simple physical picture has been proposed in order to interpret the rheological response of studied nanocomposites. 相似文献
45.
Rossella Basilotta Deborah Mannino Alessia Filippone Giovanna Casili Angela Prestifilippo Lorenzo Colarossi Gabriele Raciti Emanuela Esposito Michela Campolo 《Molecules (Basel, Switzerland)》2021,26(13)
Since cancer is a multifactorial disease with a high mortality rate, the study of new therapeutic strategies is one of the main objectives in modern research. Numerous chemotherapeutic agents, although widely used, have the disadvantage of being not very soluble in water or selective towards cancerous cells, with consequent side effects. Therefore, in recent years, a greater interest has emerged in innovative drug delivery systems (DDSs) such as calixarene, a third-generation supramolecular compound. Calixarene and its water-soluble derivatives show good biocompatibility and have low cytotoxicity. Thanks to their chemical–physical characteristics, calixarenes can be easily functionalized, and by itself can encapsulate host molecules forming nanostructures capable of releasing drugs in a controlled way. The encapsulation of anticancer drugs in a calixarene derivate improves their bioavailability and efficacy. Thus, the use of calixarenes as carriers of anticancer drugs could reduce their side effects and increase their affinity towards the target. This review summarizes the numerous research advances regarding the development of calixarene nanoparticles capable of encapsulating various anticancer drugs. 相似文献
46.
Andreas Sperlich Moritz Liedtke Julia Kern Hannes Kraus Carsten Deibel Salvatore Filippone Juan Luis Delgado Nazario Martín Vladimir Dyakonov 《固体物理学:研究快报》2011,5(3):128-130
Photoinduced polarons in solid films of polymer:fullerene blends were studied by photoluminescence (PL), photoinduced absorption (PIA) and electron spin resonance (ESR). The donor materials used were P3HT and MEH‐PPV. As acceptors we employed PC60BM as reference and various soluble C70‐derivates: PC70BM, two different diphenylmethano‐[70]fullerene oligoether (C70‐DPM‐OE) and two dimers, C70–C70 and C60–C70. Blend films containing C70 revealed characteristic spectroscopic signatures not seen with C60. Light‐induced ESR showed signals at g ≥ 2.005, assigned to an electron localized on the C70 cage. The formation of C70 radical anions also leads to a subgap PIA band at 0.92 eV, hidden in the spectra of C70‐based P3HT and MEH‐PPV blends, which allows for more exact studies of charge separated states in conjugated polymer:C70 blends. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
47.
We investigate the dynamical charge response of the Anderson model viewed as a quantum RC circuit. Applying a low-energy effective Fermi liquid theory, a generalized Korringa-Shiba formula is derived at zero temperature, and the charge relaxation resistance is expressed solely in terms of static susceptibilities which are accessible by Bethe ansatz. We identify a giant charge relaxation resistance at intermediate magnetic fields related to the destruction of the Kondo singlet. The scaling properties of this peak are computed analytically in the Kondo regime. We also show that the resistance peak fades away at the particle-hole symmetric point. 相似文献
48.
Orazio A. Attanasi Lucia De Crescentini Paolino Filippone Samuele Lillini 《Tetrahedron letters》2007,48(14):2449-2451
New tetrahydro-3aH-cyclopenta[d][1,3]thiazolines and hexahydro-1,3-benzothiazolines were obtained in satisfactory yields by reaction of cycloalkenyl-1-diazenes with thioamides. These thiazolines were converted into unknown fused cycloalkyl-thiazoline-pyrazole systems. 相似文献
49.
Capuano G Filippone G Romeo G Acierno D 《Langmuir : the ACS journal of surfaces and colloids》2012,28(12):5458-5463
We study the structure and linear viscoelasticity of interacting polymer nanocomposites based on mixtures of poly(ethylene oxide) and fumed silica particles. The filler is dispersed within the polymer using two different techniques which lead to different dispersion states. The analysis of the dynamic response of our systems highlights the formation of a stress-bearing network above a critical volume fraction, Φ(c). Extending a two-phase model used to describe weakly interacting systems, we show that above Φ(c) the melt-state elasticity of the composites arises from the independent contributions of a polymer-particle network and a viscous matrix. We also find that, although Φ(c) depends on the initial state of dispersion, the network elasticity scales with volume fraction following a universal power-law, with an exponent ν ≈ 1.8. Such a scaling law has been recently predicted for the stress-bearing mechanism governed by polymer-mediated interactions. 相似文献
50.