排序方式: 共有61条查询结果,搜索用时 15 毫秒
51.
Svetoslava Vankova Daniele Versaci Julia Amici Anna Ferrari Rosanna Rizzi Angela Altomare Salvatore Guastella Carlotta Francia Silvia Bodoardo Nerino Penazzi 《Journal of Solid State Electrochemistry》2017,21(12):3381-3388
Silicate materials have been proposed as alternative cathodes for Li-ion battery applications. A novel mixture of silicates, labelled Li6MnSi5, based on the molar ratio among the Li/Mn/Si precursors, with promising electrochemical properties as positive electrode material is synthesized through a solid-state reaction. The results indicate the proposed synthetic method as effective for preparation of nanostructured silicate powders with average particle diameter of 30 nm. Structural morphology of the samples was determined using X-ray powder diffraction (XRPD), XPS and FESEM analysis. A joint analysis by XRPD data and by density functional theory (DFT) identified LiHMn4Si5O15, Li2Mn4Si5O15, Li2Si2O5 and Li0.125Mn0.875SiO4 as components of Li6MnSi5 mixture. The electrochemical performance of Li6MnSi5 was evaluated by charge/discharge testing at constant current mode. Li6MnSi5 discharge behaviour is characterized by high capacity value of 480 mA h g?1, although such capacity fades gradually on cycling. Ex situ XPS studies carried out on the electrode in both full charged and discharged states pointed out that Li2Si2O5 is decisive for achieving such high capacity. The discharge/charge plateau is most probably related to the change in the oxidation state of silicon at the surface of the silica material. 相似文献
52.
Dr. Carlotta Foletti Dr. Rolf A. Kramer Dr. Harald Mauser Prof. Dr. Urs Jenal Dr. Konrad H. Bleicher Prof. Dr. Helma Wennemers 《Angewandte Chemie (International ed. in English)》2018,57(26):7729-7733
c‐di‐GMP is an attractive target in the fight against bacterial infections since it is a near ubiquitous second messenger that regulates important cellular processes of pathogens, including biofilm formation and virulence. Screening of a combinatorial peptide library enabled the identification of the proline‐rich tetrapeptide Gup‐Gup‐Nap‐Arg, which binds c‐di‐GMP selectively over other nucleotides in water. Computational and CD spectroscopic studies provided a possible binding mode of the complex and enabled the design of a pentapeptide with even higher binding strength towards c‐di‐GMP. Biological studies showed that the tetrapeptide inhibits biofilm growth by the opportunistic pathogen P. aeruginosa. 相似文献
53.
A greedy randomized adaptive search procedure (GRASP) is proposed for the approximate solution of general mixed binary programming problems (MBP). Examples are provided of practical applications that can be formulated as MBP requiring the solution of a large number of problem instances. This justifies, from both a practical and a theoretical perspective, the development of stopping rules aimed at controlling the number of iterations in a GRASP. To this end, a bayesian framework is laid down, two different prior distributions are proposed and stopping conditions are explicitly derived in analytical form. Numerical evidence shows that the stopping rules lead to an optimal trade-off between accuracy and computational effort, saving from unneeded iterations and still achieving good approximations. 相似文献
54.
Rida T. Farouki Graziano Gentili Carlotta Giannelli Alessandra Sestini Caterina Stoppato 《Advances in Computational Mathematics》2017,43(1):1-24
A rotation–minimizing frame (f 1,f 2,f 3) on a space curve r(ξ) defines an orthonormal basis for \(\mathbb {R}^{3}\) in which \(\mathbf {f}_{1}=\mathbf {r}^{\prime }/|\mathbf {r}^{\prime }|\) is the curve tangent, and the normal–plane vectors f 2, f 3 exhibit no instantaneous rotation about f 1. Polynomial curves that admit rational rotation–minimizing frames (or RRMF curves) form a subset of the Pythagorean–hodograph (PH) curves, specified by integrating the form \(\mathbf {r}^{\prime }(\xi )=\mathcal {A}(\xi )\,\mathbf{i} \,\mathcal {A}^{*}(\xi )\) for some quaternion polynomial \(\mathcal {A}(\xi )\). By introducing the notion of the rotation indicatrix and the core of the quaternion polynomial \(\mathcal {A}(\xi )\), a comprehensive characterization of the complete space of RRMF curves is developed, that subsumes all previously known special cases. This novel characterization helps clarify the structure of the complete space of RRMF curves, distinguishes the spatial RRMF curves from trivial (planar) cases, and paves the way toward new construction algorithms. 相似文献
55.
Gabriele Gabrielli Fabrizio Melani Sara Bernasconi Carlotta Lunghi Barbara Richichi Patrick Rollin 《Journal of carbohydrate chemistry》2013,32(3):124-141
Improved synthesis of 1,3-disaccharides, obtained diastereomerically pure by [4+2] hetero cycloadditions between glycals and α -thiono-β -keto-δ -lactones, has been reported. The choice of appropriate protecting groups for β -keto-δ -lactones, stable under cycloaddition conditions employed, sensibly shortened the synthesis of heterodienic precursors. The first example of a β -oxy-imino-δ -lactone synthesized from β -keto-δ -lactones was also reported. Molecular modeling and conformational evaluations about the cycloaddition features allowed tentatively rationalizing the experimental results. 相似文献
56.
Chang Liu Norbert Neumeister Nicola Amapane Cristina Fernandez Bedoya Riccardo Bellan Philipp Biallass Sara Bolognesi Gianluca Cerminara Mary-Cruz Fouz Iglesias Marina Giunta Luigi Guiducci Kerstin Hoepfner Stefano Lacaprara Gianni Masetti Anna Meneguzzo Pierluigi Paolucci Jesus Puerta Pelayo Riccardo Travaglini Marco Zanetti Carlos Villanueva 《The European Physical Journal C - Particles and Fields》2008,56(3):449-460
The powerful muon and tracker systems of the CMS detector together with dedicated reconstruction software allow precise and
efficient measurement of muon tracks originating from proton-proton collisions. The standard muon reconstruction algorithms,
however, are inadequate to deal with muons that do not originate from collisions. This note discusses the design, implementation,
and performance results of a dedicated cosmic muon track reconstruction algorithm, which features pattern recognition optimized
for muons that are not coming from the interaction point, i.e., cosmic muons and beam-halo muons. To evaluate the performance
of the new algorithm, data taken during Cosmic Challenge phases I and II were studied and compared with simulated cosmic data.
In addition, a variety of more general topologies of cosmic muons and beam-halo muons were studied using simulated data to
demonstrate some key features of the new algorithm. 相似文献
57.
Rida T. Farouki Carlotta Giannelli Alessandra Sestini 《Advances in Computational Mathematics》2013,38(1):63-82
When a moving (real or virtual) camera images a stationary object, the use of a rotation-minimizing directed frame (RMDF) to specify the camera orientation along its path yields the least apparent rotation of the image. The construction of such motions, using curves that possess rational RMDFs, is considered herein. In particular, the construction entails interpolation of initial/final camera positions and orientations, together with an initial motion direction. To achieve this, the camera path is described by a rational space curve that has a rational RMDF and interpolates the prescribed data. Numerical experiments are used to illustrate implementation of the method, and sufficient conditions on the two end frame orientations are derived, to ensure the existence of exactly one interpolant. By specifiying a sequence of discrete camera positions/orientations and an initial motion direction, the method can be used to construct general rotation-minimizing camera motions. 相似文献
58.
Carlotta Marianecci Luisa Di Marzio Federica Rinaldi Christian Celia Donatella Paolino Franco Alhaique Sara Esposito Maria Carafa 《Advances in colloid and interface science》2014
Efficient and safe drug delivery has always been a challenge in medicine. The use of nanotechnology, such as the development of nanocarriers for drug delivery, has received great attention owing to the potential that nanocarriers can theoretically act as “magic bullets” and selectively target affected organs and cells while sparing normal tissues. During the last decades the formulation of surfactant vesicles, as a tool to improve drug delivery, brought an ever increasing interest among the scientists working in the area of drug delivery systems. Niosomes are self assembled vesicular nanocarriers obtained by hydration of synthetic surfactants and appropriate amounts of cholesterol or other amphiphilic molecules. Just like liposomes, niosomes can be unilamellar or multilamellar, are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site. Furthermore, niosomal vesicles, that are usually non-toxic, require less production costs and are stable over a longer period of time in different conditions, so overcoming some drawbacks of liposomes. 相似文献
59.
Cesare Bracco Carlotta Giannelli Francesca Mazzia Alessandra Sestini 《BIT Numerical Mathematics》2016,56(4):1165-1188
Spline quasi-interpolation (QI) is a general and powerful approach for the construction of low cost and accurate approximations of a given function. In order to provide an efficient adaptive approximation scheme in the bivariate setting, we consider quasi-interpolation in hierarchical spline spaces. In particular, we study and experiment the features of the hierarchical extension of the tensor-product formulation of the Hermite BS quasi-interpolation scheme. The convergence properties of this hierarchical operator, suitably defined in terms of truncated hierarchical B-spline bases, are analyzed. A selection of numerical examples is presented to compare the performances of the hierarchical and tensor-product versions of the scheme. 相似文献
60.
Fisicaro E Compari C Biemmi M Duce E Peroni M Donofrio G Sansone F Rózycka-Roszak B Pruchnik H Barbero N Viscardi G Quagliotto P 《The journal of physical chemistry. B》2008,112(31):9360-9370
Thermodynamic properties of aqueous solutions of newly synthesized compounds, namely, N-[2-(beta-D-glucopyranosyl)ethyl]-N,N-dimethyl-N-alkylammonium bromides with hydrophobic tails of 12 (C12DGCB) and 16 (C16DGCB) carbon atoms, determined as a function of concentration by means of direct methods, are reported here. Dilution enthalpies, densities, and sound velocities were measured at 298 K, allowing for the determination of apparent and partial molar enthalpies, volumes, and compressibilities. Changes in thermodynamic quantities upon micellization were derived using a pseudophase-transition approach. From a comparison with the corresponding acetylated compounds N-[2-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)ethyl]-N,N-dimethyl-N-dodecylammonium bromide (C12AGCB) and N-[2-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyanosyl)ethyl]-N,N-dimethyl-N-hexadecylammonium bromide (C16AGCB), the role played in the micellization process by the acetylated glycosyl moiety was inferred: it enhances the hydrophobic character of the molecule and lowers the change in enthalpy of micelle formation by about 1.5 kJ mol(-1). By comparing the volume of C12DGCB with those of DEDAB and DTAB, the volumes taken up by the (beta- d-glucopyranosyl)ethyl and beta- d-glucopyranosyl groups were found to be 133 and 99 cm3 mol(-1), respectively. Regarding the interaction with DPPC membranes, it seems that the sugar moiety of the hexadecyl deacetylated compound gives rise to hydrogen bonds with the oxygen atoms of the lipid phosphates, shifting the phase transition of DPPC from a bilayer gel to a bilayer liquid crystal to lower temperatures. C16AGCB induces significantly greater changes than C16DGCB in the structure of liposomes, suggesting the formation of domains. The interaction is strongly enhanced by the presence of water. Neither compound interacts strongly with DNA or compacts it, as shown by EMSA assays and AFM images. Only C16AGCB is able to deliver little DNA inside cells when coformulated with DOPE, as shown by the transient transfection assay. This might be related to the ability of C16AGCB to form surfactant-rich domains in the lipid structure. 相似文献