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排序方式: 共有217条查询结果,搜索用时 15 毫秒
1.
Virginia Veronica Visconti Ida Cariati Simona Fittipaldi Riccardo Iundusi Elena Gasbarra Umberto Tarantino Annalisa Botta 《International journal of molecular sciences》2021,22(8)
DNA methylation is one of the most studied epigenetic mechanisms that play a pivotal role in regulating gene expression. The epigenetic component is strongly involved in aging-bone diseases, such as osteoporosis and osteoarthritis. Both are complex multi-factorial late-onset disorders that represent a globally widespread health problem, highlighting a crucial point of investigations in many scientific studies. In recent years, new findings on the role of DNA methylation in the pathogenesis of aging-bone diseases have emerged. The aim of this systematic review is to update knowledge in the field of DNA methylation associated with osteoporosis and osteoarthritis, focusing on the specific tissues involved in both pathological conditions. 相似文献
2.
Maria Chiara Mistretta Luigi Botta Francesco Paolo La Mantia Antonino Di Fiore Marco Cascone 《大分子材料与工程》2021,306(9):2100177
Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer blend and two different inorganic nanofillers (an organo-modified clay and a calcium carbonate with a hydrophobic coating) are used for the preparation of the nanocomposites. A detailed investigation of obtained materials is performed through rheological, mechanical, and optical characterizations. Adding nanofillers led to an increase of rigidity and tear strength of blown films without negatively affecting their ductility. 相似文献
3.
Thomas Silverston Olivier Fourmaux Alessio Botta Alberto Dainotti Antonio Pescapé Giorgio Ventre Kavé Salamatian 《Computer Networks》2009,53(4):470-484
The Internet is currently experiencing one of the most important challenges in terms of content distribution since its first uses as a medium for content delivery: users from passive downloaders and browsers are moving towards content producers and publishers. They often distribute and retrieve multimedia contents establishing network communities. This is the case of peer-to-peer IPTV communities.In this work we present a detailed study of P2P IPTV traffic, providing useful insights on both transport- and packet-level properties as well as on the behavior of the peers inside the network. In particular, we provide novel results on the (i) ports and protocols used; (ii) differences between signaling and video traffic; (iii) behavior of the traffic at different time scales; (iv) differences between TCP and UDP traffic; (v) traffic generated and received by peers; (vi) peers neighborhood and session duration. The knowledge gained thanks to this analysis is useful for several tasks, e.g. traffic identification, understanding the performance of different P2P IPTV technologies and the impact of such traffic on network nodes and links, and building more realistic models for simulations.1 相似文献
4.
5.
R. Floriano S. Deledda B.C. Hauback D.R. Leiva W.J. Botta 《International Journal of Hydrogen Energy》2017,42(10):6810-6819
In this study, powder mixtures of MgH2 + 2 mol.% X, with X = Nb, Nb2O5, NbF5, Fe, Fe2O3, FeF3, were processed by mechanical milling at liquid nitrogen temperature (cryomilling). The effect of additives on crystalline structure, thermal properties and hydrogen storage properties of the mixtures were investigated. Morphological investigations indicated a heterogeneous particle size distribution of the powder mixtures and a fine dispersion of additive particles (FeF3) in the MgH2 matrix. High resolution synchrotron radiation X-ray diffraction (SR-XRD) data followed by Rietveld refinements showed a significant reduction on crystallite size for the samples containing fluorides (11 nm) in comparison with the pure MgH2 sample (29 nm). This was related to the mechanical behavior of fluorides during milling with MgH2, which act as a lubricant, dispersing and/or cracking agent during milling, and thus helping to further reduce MgH2 particle size. DSC analysis revealed that fluorides (NbF5, FeF3) are much more effective than oxides (Nb2O5, Fe2O3) and the transition metals (Nb and Fe), respectively, in reduction the desorption temperature. Furthermore, Nb2O5 is more efficient than Fe2O3. Finally, the best results for desorption kinetics were observed for the fluorides: NbF5 and FeF3 (equivalent effect and consistent to the DSC analysis) followed by the oxides: Nb2O5, Fe2O3 and Nb. The addition of Fe was not efficient in comparison with the pure cryomilled sample. 相似文献
6.
7.
Morteza Ganjaee Sari Norbert Stribeck Siamak Moradian Ahmad Zeinolebadi Saeed Bastani Stephan Botta Ehsan Bakhshandeh 《Polymer International》2014,63(2):195-205
Polypropylene (PP) was modified utilizing two types of polyesteramide‐based hyperbranched polymers (amphiphilic PS and hydrophilic PH). A maleicanhydride‐modified PP (PM) was used as a reactive dispersing agent to enhance the modification by grafting the hyperbranched polymers onto the PP chains. Pure PP, two different non‐reactively modified samples, i.e. excluding PM, and two different reactively modified samples, i.e. including PM, were studied. Investigating the morphology of the samples was performed by scanning electron microscopy. To follow the effect of the modification on the dynamic mechanical properties, dynamic mechanical analysis experiments both in the melt (rheometric mechanical spectrometry) and in solid state (dynamic mechanical thermal analysis) were carried out. In the next step, the nanocrystalline structure of the samples was studied by small angle X‐ray scattering (SAXS) in two different modes, i.e. static and recrystallization. Hundreds of SAXS patterns were analyzed automatically using procedures written in PV‐WAVE image‐processing software. The chord distribution function (CDF) was calculated and the long period (lp) of the crystal lamellae was extracted from the CDFs. The rheometric mechanical spectrometry results show that both hyperbranched polymers decrease complex viscosity η* and enhance liquid‐like behavior. This happens more significantly when PM is included. The dynamic mechanical thermal analysis results reveal that Tg decreases when PS and PH are added. In the reactively modified samples this reduction is compensated most probably because of the crosslinked structure formed through the grafting reaction between the hyperbranched polymers and PM. Such structure is confirmed by SAXS data and calculated CDFs in the recrystallization mode. Static SAXS data also show enhancement in the crosshatched morphology of the crystalline lamellae of PP for reactively modified samples compared with non‐reactively modified samples. © 2013 Society of Chemical Industry 相似文献
8.
R. Scaffaro L. Botta M.C. Mistretta F. Caradonna 《Reactive and Functional Polymers》2010,70(3):189-200
In this work, we present the results of a kinetic study of the surface modification of the carboxyl group of poly(ethylene-co-acrylic acid) into acyl chloride. Reaction temperature and time, concentration of the reactants, kind of agitation have been changed in order to understand their effect on the conversion. A study on the penetration of the reaction inside the sample bulk was also performed. The results indicate that, when short reaction times are adopted, the reaction limits to the outer layers of the samples and, in this case, on increasing the temperature, the concentration of the reactants and the stirring allows having a faster kinetic. At longer reaction times, the reaction penetrates deep inside the sample (several tens of microns) and the influence of the above mentioned variables on the kinetic is very low.The results, obtained by direct FTIR, ATR-FTIR, SEM–EDX and contact angle measurements, were confirmed and corroborated by theoretical estimations. 相似文献
9.
A 20% reduction in the consumption of energy is one of the main goals of the European Union’s (EU) 20/20/20 Energy Strategy. But the uniform application of this overall goal to all of the countries is neither fair nor equitable, as it does not take into consideration the characteristics of the energy system in each Member State. This article therefore proposes a nonlinear distribution methodology with objective, dynamic goals for reducing gross inland energy consumption, according to the context and characteristics of each member state. We hope it will open discussion on how these overall goals can be weighted. Then we analyse the situation of the energy indicators related to energy efficiency in the reference year (2005) used by the EU for reaching its goal of reducing the gross inland consumption by 20% by 2020, and its progress from 1996 to 2007. Finally, the methodology proposed is applied to the year 2020 on the NUTS0 territorial level, that is, to members of the EU, according to the EUROSTAT Nomenclature of Territorial Units for Statistics (NUTS). Weighting is done based on energy intensity, per capita gross inland consumption and per capita energy intensity in two scenarios, the EU-15 and EU-27. 相似文献
10.
In recent years, researchers have begun to study inductive databases, a new generation of databases for leveraging decision support applications. In this context, the user interacts with the
DBMS using advanced, constraint-based languages for data mining where constraints have been specifically introduced to increase
the relevance of the results and, at the same time, to reduce its volume. In this paper we study the problem of mining frequent
itemsets using an inductive database. We propose a technique for query answering which consists in rewriting the query in
terms of union and intersection of the result sets of other queries, previously executed and materialized. Unfortunately,
the exploitation of past queries is not always applicable. We then present sufficient conditions for the optimization to apply
and show that these conditions are strictly connected with the presence of functional dependencies between the attributes
involved in the queries. We show some experiments on an initial prototype of an optimizer which demonstrates that this approach
to query answering is viable and in many practical cases it drastically reduces the query execution time. 相似文献