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Mega MS Allegrini P Grigolini P Latora V Palatella L Rapisarda A Vinciguerra S 《Physical review letters》2003,90(18):188501
We study the statistical properties of time distribution of seismicity in California by means of a new method of analysis, the diffusion entropy. We find that the distribution of time intervals between a large earthquake (the main shock of a given seismic sequence) and the next one does not obey Poisson statistics, as assumed by the current models. We prove that this distribution is an inverse power law with an exponent mu=2.06+/-0.01. We propose the long-range model, reproducing the main properties of the diffusion entropy and describing the seismic triggering mechanisms induced by large earthquakes. 相似文献
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Shang‐Zheng Sun Yaya Duan Riccardo S. Mega Rosie J. Somerville Ruben Martin 《Angewandte Chemie (International ed. in English)》2020,59(11):4370-4374
A modular, site‐selective 1,2‐dicarbofunctionalization of vinyl boronates with organic halides through dual catalysis is described. This reaction proceeds under mild conditions and is characterized by excellent chemo‐ and regioselectivity. It thus represents a complementary new technique for preparing densely functionalized alkyl boron architectures from simple and accessible precursors. 相似文献
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Desyana Olenka Margaretta Mega Silvia Lestari Bebeh W. Nuryadin Mikrajuddin Abdullah 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(6):154
We introduce a new and general criterion for melting as an alternative to the commonly used Lindemann criterion. Nanostructures are modeled using a zipper model and the melting process is assumed to start from the outer layer and develop towards the center layer. Melting occurs when the logarithm of the partition function per number of layers is zero. The equation shows good consistency with experimental data for the melting of thin films, nanoparticles, and nanowires. We also introduce a degree-of-freedom parameter which seems to be universal for most metals. 相似文献
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Decarboxylative Conjunctive Cross-coupling of Vinyl Boronic Esters using Metallaphotoredox Catalysis
Riccardo S. Mega Vincent K. Duong Dr. Adam Noble Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4405-4409
The synthesis of complex alkyl boronic esters through conjunctive cross-coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross-coupling cascade of vinyl boronic esters. Excellent functional-group tolerance is displayed, and application of a range of carboxylic acids, including secondary α-amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross-coupling was also applied to the synthesis of sedum alkaloids. 相似文献
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Élida B. Hermida Verónica I. Mega Oxana Yashchuk Víctor Fernández Patricia Eisenberg Silvia S. Miyazaki 《Macromolecular Symposia》2008,263(1):102-113
Summary: Their biodegradable properties make polyhydroxyalkanoates (PHAs) ideal candidates for innovative applications. Many studies have been primarily oriented to poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-valerate) (PHBV) and afterwards to blends of PHAs with synthetic biodegradable polymers, such as poly(ε-caprolactone) (PCL). Medical and pharmaceutical devices require sterilization and γ irradiation could provide a proper alternative since it assures storage stability and microbiological safety. This contribution presents the effect of γ irradiation on the mechanical and thermal properties and on the biodegradation of PHB, PHBV and a commercial PHB/PCL blend. Samples, prepared by compression moulding, were irradiated in air at a constant dose rate of 10 kGy/h, from 10 to 179 kGy. Polymer chain scission was assessed by changes in the molecular weight, thermal properties and tensile behaviour. The correlation between absorbed dose and changes in the mechanical properties and biodegradation is discussed in detail. The optimum dose to guarantee microbiological sterilization without damage of the structure or meaningful loss of the mechanical properties is also reported. 相似文献
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Visible‐Light‐Mediated Decarboxylative Radical Additions to Vinyl Boronic Esters: Rapid Access to γ‐Amino Boronic Esters
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Dr. Adam Noble Riccardo S. Mega Dr. Daniel Pflästerer Dr. Eddie L. Myers Prof. Dr. Varinder K. Aggarwal 《Angewandte Chemie (International ed. in English)》2018,57(8):2155-2159
The synthesis of alkyl boronic esters by direct decarboxylative radical addition of carboxylic acids to vinyl boronic esters is described. The reaction proceeds under mild photoredox catalysis and involves an unprecedented single‐electron reduction of an α‐boryl radical intermediate to the corresponding anion. The reaction is amenable to a diverse range of substrates, including α‐amino, α‐oxy, and alkyl carboxylic acids, thus providing a novel method to rapidly access boron‐containing molecules of potential biological importance. 相似文献
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Shang-Zheng Sun Yaya Duan Riccardo S. Mega Rosie J. Somerville Prof. Ruben Martin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4400-4404
A modular, site-selective 1,2-dicarbofunctionalization of vinyl boronates with organic halides through dual catalysis is described. This reaction proceeds under mild conditions and is characterized by excellent chemo- and regioselectivity. It thus represents a complementary new technique for preparing densely functionalized alkyl boron architectures from simple and accessible precursors. 相似文献