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T. M. Shneidman A. V. Andreev C. Massimi M. T. Pigni G. Vannini A. Ventura S. G. Zhou 《原子核物理评论》2015,32(2):175-179
A theoretical evaluation of the collective excitation spectra of nucleus at large deformations is possible within the framework of the dinuclear system (DNS) model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two-cluster configurations in a dynamical way, permitting exchange of nucleons between clusters. In this work the method of calculation of the potential energy and the collective spectrum of fissioning nucleus at scission point is presented. Combining the DNS model calculations and the statistical model of fission we calculate the angular distribution of fission fragments for the neutron–induced fission of 239Pu. 相似文献
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Compliance and enforcement in fisheries are important issues from an economic point of view since management measures are useless without a certain level of enforcement. These conclusions come from the well‐established theoretical literature on compliance and enforcement problems within fisheries and a common result is that, it is efficient to set fines as high as possible and monitoring as low as possible, when fines are costless and offenders are risk neutral. However, this result is sensitive to the assumption that fishermen cannot engage in avoidance activities, e.g., activities to reduce the likelihood of being detected when noncomplying. The paper presents a model of fisheries that allows the fishermen to engage in avoidance activities. The conclusions from the model are that, under certain circumstances, fines are costly transfers to society since they not only have a direct positive effect on the level of deterrence, but also an indirect negative effect in the form of increased avoidance activities to reduce the probability of detection. The paper contributes to the literature on avoidance activities by introducing the externality from the illegal behavior as an endogenous effect on other offenders. For an externality, that has an exogenous effect on other actors, Malik shows that fines are only costly transfers for conditional deterrence (when one actor is deterred while another actor is not). For fisheries, we show that fines are also costly transfers under no deterrence (when no agents are deterred). 相似文献
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Kevin Clark Natalia B. Pigni Kithmini Wijesiri Jos A. Gascn 《Molecules (Basel, Switzerland)》2021,26(9)
The increased interest in sequencing cyanobacterial genomes has allowed the identification of new homologs to both the N-terminal domain (NTD) and C-terminal domain (CTD) of the Orange Carotenoid Protein (OCP). The N-terminal domain homologs are known as Helical Carotenoid Proteins (HCPs). Although some of these paralogs have been reported to act as singlet oxygen quenchers, their distinct functional roles remain unclear. One of these paralogs (HCP2) exclusively binds canthaxanthin (CAN) and its crystal structure has been recently characterized. Its absorption spectrum is significantly red-shifted, in comparison to the protein in solution, due to a dimerization where the two carotenoids are closely placed, favoring an electronic coupling interaction. Both the crystal and solution spectra are red-shifted by more than 50 nm when compared to canthaxanthin in solution. Using molecular dynamics (MD) and quantum mechanical/molecular mechanical (QM/MM) studies of HCP2, we aim to simulate these shifts as well as obtain insight into the environmental and coupling effects of carotenoid–protein interactions. 相似文献
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Pigni NB Berkov S Elamrani A Benaissa M Viladomat F Codina C Bastida J 《Molecules (Basel, Switzerland)》2010,15(10):7083-7089
The Amaryllidaceae family is well known for the presence of an exclusive group of alkaloids with a wide range of biological activities. Narcissus serotinus L. is a plant belonging to this family and its geographical distribution is mainly located along the Mediterranean coast. In the present work, specimens collected near Casablanca (Morocco) were used to study the alkaloid content of this species. Starting with 350 g of the whole plant we used standard extraction and purification procedures to obtain fractions and compounds for GC-MS and NMR analysis. As well as five known alkaloids, we isolated two new compounds: 1-O-(3′-acetoxybutanoyl)lycorine and narseronine. The latter has been previously published, but with an erroneous structure. 相似文献
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E. Gadioli G.F. Steyn F. Albertini C. Birattari M. Cavinato S.H. Connell A.A. Cowley E. Fabrici S.V. Förtsch E. Gadioli Erba J.J. Lawrie M. Pigni J.P.F. Sellschop E. Sideras Haddad 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):195-212
In this paper we study the emission of 8Begs, B and N fragments in the interaction of 16O ions with 59Co, 93Nb and 197Au at incident energies varying from 6 to 25 MeV/nucleon. The spectra of these fragments, as well as those of C fragments
studied in a previous paper, are dominated at forward angles by a component originating from break-up of 16O. At the higher incident energies break-up occurs after quite a sizeable projectile energy loss. Another mechanism which
dominates at large emission angles, favours the emission of low-energy fragments and is attributed to the coalescence of nucleons
during the cascade of nucleon-nucleon interactions by means of which the excited nuclei produced in the primary two-ion interaction
thermalize.
Received: 21 January 2003 / Accepted: 27 March 2003 / Published online: 5 June 2003 相似文献
6.
Ying Guo Jean P. de Andrade Natalia B. Pigni Laura Torras‐Claveria Luciana R. Tallini Warley de S. Borges Francesc Viladomat Jerald J. Nair José A. S. Zuanazzi Jaume Bastida 《Helvetica chimica acta》2016,99(2):143-147
A new phytochemical study of the indigenous Brazilian species Hippeastrum papilio is reported herein. Three novel Amaryllidaceae alkaloids were isolated, including hippapiline ( 1 ), papiline ( 2 ), and 3‐O‐demethyl‐3‐O‐(3‐hydroxybutanoyl)haemanthamine ( 3 ). Their structures were determined by physical and spectroscopic methods. In addition, the known alkaloids, haemanthamine ( 4 ), galanthamine ( 5 ), narwedine ( 6 ), 11β‐hydroxygalanthamine ( 7 ), apogalanthamine ( 8 ), and 9‐O‐demethyllycosinine B ( 9 ) were identified. The unusual cis‐B/C‐ring fusion for the new homolycorine representative hippapiline was ratified by NMR and CD spectroscopy. 相似文献
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