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921.
Nicoletta Calace Andrea Casagrande Sabrina Mirante Bianca Maria Petronio Marco Pietroletti 《Microchemical Journal》2010,96(2):218-224
Dissolved (DFA) and particulate (PFA) fulvic acids were studied in some areas of the Ross Sea (Antarctica) characterised by different water masses. Our interest was focused on their distribution in the water column. Moreover, their correlation with fluorescence data and structural characterisation in relation to the water masses was also studied. We found that PFA concentration was mainly influenced by the primary production in surface layers and by stratification of water masses along the water column. Conversely, the DFA are less influenced by primary production and by the stratification of the water masses. An early stage of the humification process can be hypothesised for PFA related to DFA as shown by elemental analyses and spectroscopic data. PFA collected in the bottom depths of the water column showed a relationship with age of water mass (the highest concentration was found for the oldest circulating water mass (CDW)). This relationship was not observed for DFA. Moreover, any significant difference in structure was found in the DFA and PFA extracted from samples collected at bottom depths. 相似文献
922.
We study solutions to the free stochastic differential equation , where V is a locally convex polynomial potential in m non-commuting variables and S an m-dimensional free Brownian motion. We prove that such free processes have a unique stationary distribution μV. When the potential V is self-adjoint, we show that the law μV is the limit law of a random matrix model, in which an m-tuple of self-adjoint matrices are chosen according to the law exp.
If V = Vβ depends on complex parameters , we prove that the moments of the law μV are analytic in β at least for those β for which Vβ is locally convex. In particular, this gives information on the region of convergence of the generating function for the
enumeration of related planar maps.
We prove that the solution Xt has nice convergence properties with respect to the operator norm as t goes to infinity. This allows us to show that the C* and W* algebras generated by an m-tuple with law μV share many properties with those generated by a semi-circular system. Among them is the lack of projections, exactness, the
Haagerup property, and embeddability into the ultrapower of the hyperfinite II1 factor. We show that the microstates free entropy χ(μV ) is finite when V is self-adjoint.
A corollary of these results is the fact that the support of the law of any self-adjoint polynomial in under the law μV is connected, vastly generalizing the case of a single random matrix.
We also deduce from this dynamical approach that the convergence of the operator norms of independent matrices from the GUE
proved by Haagerup and Thorbjornsen [HT] extends to the context of matrices interacting via a convex potential.
Received: February 2007, Revision: July 2007, Accepted: July 2007 相似文献
923.
Alice Benzi Lara Bianchi Gianluca Giorgi Massimo Maccagno Giovanni Petrillo Domenico Spinelli Cinzia Tavani 《Molecules (Basel, Switzerland)》2022,27(10)
Nitrostilbenes characterized by two different or differently substituted aryl moieties can be obtained from the initial ring-opening of 3-nitrobenzo[b]thiophene with amines. Such versatile building blocks couple the well-recognized double electrophilic reactivity of the nitrovinyl moiety (addition to the double bond, followed by, e.g., intramolecular replacement of the nitro group) with the possibility to exploit a conjugated system of double bonds within an electrocyclization process. Herein, nitrostilbenes are reacted with different aromatic enols provided by a double (carbon and oxygen) nucleophilicity, leading to novel, interesting naphthodihydrofurans. From these, as a viable application, aromatization and electrocyclization lead in turn to valuable polycondensed, fully aromatic O-heterocycles. 相似文献
924.
Alice Romeo Federico Iacovelli Carolina Scagnolari Mirko Scordio Federica Frasca Roberta Cond Serena Ammendola Roberta Gaziano Maurizio Anselmi Maurizio Divizia Mattia Falconi 《Molecules (Basel, Switzerland)》2022,27(12)
The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent. 相似文献
925.
Luisa Affatigato Alice Sciortino Giuseppe Sancataldo Alessio Incocciati Roberta Piacentini Alessandra Bonamore Marco Cannas Fabrizio Messina Mariano Licciardi Valeria Militello 《Photochemistry and photobiology》2023,99(5):1218-1224
Ferritin nanoparticles play many important roles in theranostic and bioengineering applications and have been successfully used as nanovectors for the targeted delivery of drugs due to their ability to specifically bind the transferrin receptor (TfR1, or CD71). They can be either genetically or chemically modified for encapsulating therapeutics or probes in their inner cavity. Here, we analyzed a new engineered ferritin nanoparticle, made of the H chain mouse ferritin (HFt) fused with a specific lanthanide binding tag (LBT). The HFt-LBT has one high affinity lanthanide binding site per each of the 24 subunits and a tryptophane residue within the tag that acts as an antenna able to transfer the energy to the lanthanide ions via a LRET process. In this study, among lanthanides, we selected europium for its red emission that allows to reduce overlap with tissue auto-fluorescence. Steady state emission measurements and time-resolved emission spectroscopy have been employed to investigate the interaction between the HFt-LBT and the Eu3+ ions. This allowed us to identify the Eu3+ energy states involved in the process and to pave the way for the future use of HFt-LBT Eu3+ complex in theranostics. 相似文献
926.
Roberto F. de Souza Osvaldo L. Casagrande Jr. 《Macromolecular rapid communications》2001,22(16):1293-1301
Several homogeneous and heterogeneous binary systems have been applied to olefin polymerization in order to produce polymers with improved physical and/or chemical characteristics. This article reviews the recent developments in this area focusing mainly on polymer properties, the relationship between the types of catalyst present in the binary systems, their use in the homopolymerization of ethylene and propene, and the copolymerization of ethylene and higher α‐olefins. 相似文献
927.
In this paper we show a new inequality that generalizes to the unit sphere the Lebedev-Milin inequality of the exponentiation of functions on the unit circle. It may also be regarded as the counterpart on the sphere of the second inequality in the Szegö limit theorem on the Toeplitz determinants on the circle. On the other hand, this inequality is also a variant of several classical inequalities of Moser-Trudinger type on the sphere. The inequality incorporates the deviation of the center of mass from the origin into the optimal inequality of Aubin for functions with mass centered at the origin, and improves Onofri's inequality with the contribution of the shifting of the mass center explicitly expressed. © 2021 Wiley Periodicals LLC. 相似文献
928.
Andrew J. Devine Dr. Alice E. Parnell Dr. Catherine R. Back Dr. Nicholas R. Lees Dr. Samuel T. Johns Ainul Z. Zulkepli Rob Barringer Dr. Katja Zorn Dr. James E. M. Stach Prof. Matthew P. Crump Prof. Martin A. Hayes Dr. Marc W. van der Kamp Prof. Paul R. Race Prof. Christine L. Willis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202213053
Abyssomicin C and its atropisomer are potent inhibitors of bacterial folate metabolism. They possess complex polycyclic structures, and their biosynthesis has been shown to involve several unusual enzymatic transformations. Using a combination of synthesis and in vitro assays we reveal that AbyV, a cytochrome P450 enzyme from the aby gene cluster, catalyses a key late-stage epoxidation required for the installation of the characteristic ether-bridged core of abyssomicin C. The X-ray crystal structure of AbyV has been determined, which in combination with molecular dynamics simulations provides a structural framework for our functional data. This work demonstrates the power of combining selective carbon-13 labelling with NMR spectroscopy as a sensitive tool to interrogate enzyme-catalysed reactions in vitro with no need for purification. 相似文献
929.
Shu Hui Wang Luiziana F. Silva Juliana Kloss Marilda Munaro Gabriel Pinto de Souza M. Alice Wada J. Gregório C. Gomez S. Zawadzki L. Akcelrud 《Macromolecular Symposia》2003,197(1):255-264
Two series of segmented polyurethanes were prepared with systematic variation in soft and hard segment length. The soft segment was constituted by polycaprolactone (PCL) blocks of molecular masses 530 or 2000 and the hard segment (HS) by urethane blocks, in a concentration that varied from 12% to 44% in weight of the whole polyurethane. Morphological analyses indicated that the amount of crystallinity of copolymers was strongly dependent on the PCL molar mass and hard segment content. The copolymers with longer PCL soft segments (Mn=2000) were semicrystalline, but those with shorter PCL segment (Mn=530) were unable to crystallize. The primary factor affectingthe biodegradability of copolymers as evaluated by Sturm tests was the extent of the phase separation, and that the segmental blending of the less biodegradable polyurethane (HS) blocks with PCL in the amorphous phase had a critical unfavorable consequence, which may be attributed to the size of the accessible area by microorganisms. 相似文献