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81.
Baker ML Bianchi A Carretta S Collison D Docherty RJ McLnnes EJ McRobbie A Muryn CA Mutka H Piligkos S Rancan M Santini P Timco GA Tregenna-Piggott PL Tuna F Güdel HU Winpenny RE 《Dalton transactions (Cambridge, England : 2003)》2011,40(12):2725-2734
We report a detailed physical analysis on a family of isolated, antiferro-magnetically (AF) coupled, chromium(III) finite chains, of general formula (Cr(RCO(2))(2)F)(n) where the chain length n = 6 or 7. Additionally, the chains are capped with a selection of possible terminating ligands, including hfac (= l,l,l,5,5,5-hexafluoropentane-2,4-dionate(l-)), acac (= pentane-2,4-dionate(l-)) or (F)(3). Measurements by inelastic neutron scattering (INS), magnetometery and electron paramagnetic resonance (EPR) spectroscopy have been used to study how the electronic properties are affected by n and capping ligand type. These comparisons allowed the subtle electronic effects the choice of capping ligand makes for odd member spin 3/2 ground state and even membered spin 0 ground state chains to be investigated. For this investigation full characterisation of physical properties have been performed with spin Hamiltonian parameterisation, including the determination of Heisenberg exchange coupling constants and single ion axial and rhombic anisotropy. We reveal how the quantum spin energy levels of odd or even membered chains can be modified by the type of capping ligand terminating the chain. Choice of capping ligands enables Cr-Cr exchange coupling to be adjusted by 0, 4 or 24%, relative to Cr-Cr exchange coupling within the body of the chain, by the substitution of hfac, acac or (F)(3) capping ligands to the ends of the chain, respectively. The manipulation of quantum spin levels via ligands which play no role in super-exchange, is of general interest to the practise of spin Hamilton modelling, where such second order effects are generally not considered of relevance to magnetic properties. 相似文献
82.
Mascaros PA Bazzicalupi C Bianchi A Giorgi C Valero MD Garzón RL Salido ML Valtancoli B 《Chemical communications (Cambridge, England)》2011,47(10):2814-2816
The synergistic action of the different binding groups of the polyfunctional HL receptor leads to the recognition of ADP over ATP in water, with a selectivity coefficient of up to 116, a phenomenon which is unprecedented in the context of synthetic receptors in water. The recognition is mostly due to the good matching between H(3)L(2+) and the protonated forms of ADP. 相似文献
83.
Monica Borgatti Irene Mancini Nicoletta Bianchi Alessandra Guerrini Ilaria Lampronti Damiano Rossi Gianni Sacchetti Roberto Gambari 《BMC biochemistry》2011,12(1):15
Background
Cystic fibrosis (CF) airway pathology is a fatal, autosomal, recessive genetic disease characterized by extensive lung inflammation. After induction by TNF-α, elevated concentrations of several pro-inflammatory cytokines (i.e. IL-6, IL-1β) and chemokines (i.e. IL-8) are released from airway epithelial cells. In order to reduce the excessive inflammatory response in the airways of CF patients, new therapies have been developed and in this respect, medicinal plant extracts have been studied. In this article we have investigated the possible use of bergamot extracts (Citrus bergamia Risso) and their identified components to alter the expression of IL-8 associated with the cystic fibrosis airway pathology. 相似文献84.
Giovanni Petrillo Cinzia Tavani Lara Bianchi Alice Benzi Maria Maddalena Cavalluzzi Lara Salvagno Laura Quintieri Annalisa De Palma Leonardo Caputo Antonio Rosato Giovanni Lentini 《Molecules (Basel, Switzerland)》2021,26(13)
Twenty-two novel, variously substituted nitroazetidines were designed as both sulfonamide and urethane vinylogs possibly endowed with antimicrobial activity. The compounds under study were obtained following a general procedure recently developed, starting from 4-nitropentadienoates deriving from a common β-nitrothiophenic precursor. While being devoid of any activity against fungi and Gram-negative bacteria, most of the title compounds performed as potent antibacterial agents on Gram-positive bacteria (E. faecalis and three strains of S. aureus), with the most potent congener being the 1-(4-chlorobenzyl)-3-nitro-4-(p-tolyl)azetidine 22, which displayed potency close to that of norfloxacin, the reference antibiotic (minimum inhibitory concentration values 4 and 1–2 μg/mL, respectively). Since 22 combines a relatively efficient activity against Gram-positive bacteria and a cytotoxicity on eucharyotic cells only at 4-times higher concentrations (inhibiting concentration on 50% of the cultured eukaryotic cells: 36 ± 10 μM, MIC: 8.6 μM), it may be considered as a promising hit compound for the development of a new series of antibacterials selectively active on Gram-positive pathogens. The relatively concise synthetic route described herein, based on widely available starting materials, could feed further structure–activity relationship studies, thus allowing for the fine investigation and optimization of the toxico-pharmacological profile. 相似文献
85.
C. Lamberti A. Antolini S. Bianchi A. Castelli M. Dellagiovanna 《Zeitschrift für Physik B Condensed Matter》1996,100(2):195-198
GaAs technology for microwave devices (MESFET and MMIC) has received a significant improvement by ion implantation of silicon to form n-type active channel regions. Owing to amphoteric behaviour of silicon in GaAs, different activation of the implanted species can be obtained, depending on the post-implantation annealing treatment. In this paper we describe the results of the influence of rapid thermal annealing on implanted GaAs and using 4 K photoluminescence spectroscopy we identify the corresponding species (SiAS and SiAS-VAS complex) in silicon doped GaAs and explain the electrical behaviour of the implanted and annealed material. 相似文献
86.
The probabilistic traveling salesman problem is a well known problem that is quite challenging to solve. It involves finding the tour with the lowest expected cost for customers that will require a visit with a given probability. There are several proposed algorithms for the homogeneous version of the problem, where all customers have identical probability of being realized. From the literature, the most successful approaches involve local search procedures, with the most famous being the 2-p-opt and 1-shift procedures proposed by Bertsimas [D.J. Bertsimas, L. Howell, Further results on the probabilistic traveling salesman problem, European Journal of Operational Research 65 (1) (1993) 68–95]. Recently, however, evidence has emerged that indicates the equations offered for these procedures are not correct, and even when corrected, the translation to the heterogeneous version of the problem is not simple. In this paper we extend the analysis and correction to the heterogeneous case. We derive new expressions for computing the cost of 2-p-opt and 1-shift local search moves, and we show that the neighborhood of a solution may be explored in O(n2) time, the same as for the homogeneous case, instead of O(n3) as first reported in the literature. 相似文献
87.
F. Bianchi A. Giovannini S. Lupia R. Ugoccioni 《Zeitschrift fur Physik C Particles and Fields》1993,58(1):71-75
By using JETSET 7.2 ase + e ? event generator at different c.m. energies, we studiedsingle jet multiplicity distributions in different rapidity andp T intervals. Good NB behavior is found and related clan structure analysis is performed. Observed differences in the behavior of the 2-and 3-jet samples can be understood in terms of the relative contribution of single quark and gluon jet to the 3-jet sample, which are obtained by selecting event by event in this sample the highest and the lowest energy jet respectively. 相似文献
88.
M. Ionita G. Cappelletti A. Minguzzi S. Ardizzone C. Bianchi S. Rondinini A. Vertova 《Journal of nanoparticle research》2006,8(5):653-660
SnO2 particles and films were prepared by following a common sol–gel preparative route using tin (IV) alkoxide as the starting compound; the xerogels were thermally treated at 300, 500 and 700°C. The materials were characterized for phase composition-crystallinity, by X-ray diffraction, and for surface area and porosity, by N2 adsorption isotherms. Both structural and morphological characterizations showed, at all temperatures, the formation of nanostructured SnO2. By cyclic voltammetry and by electrochemical impedance spectroscopy the typical semiconductive behaviour of nanostructured materials was observed; the presence of Sn surface states with lower valence with respect to Sn(IV) was supported by both impedance and XPS analyses performed, also, in the valence band region. The isoelectric point (i.e.p.) of the material and its dependence on the temperature of calcination was obtained by means of electrophoretic mobility determinations as a function of the solution pH.M. Ionita: On leave from the Faculty of Industrial Chemistry, Applied Physical Chemistry and Electrochemistry Department, University Politechnica of Bucharest 相似文献
89.
Gabriela R. Argiroffo Silvia M. Bianchi Graciela L. Nasini 《Mathematical Methods of Operations Research》2008,67(2):245-256
Lehman (Polyhedral combinatorics 1 of DIMACS series in discrete math. and theoretical computer science, pp 101–105, 1990) described some conditions regular
minimally nonideal (mni) matrices must satisfy. Although, there are few results on sufficient conditions for mni matrices.
In most of these results, the covering polyhedron must have a unique fractional extreme point. This condition corresponds
to ask the matrix to be the blocker of a near-ideal matrix, defined by the authors in a previous work (2006). In this paper
we prove that, having the blocker of a near-ideal matrix, only a few very easy conditions have to be checked in order to decide
if the matrix is regular mni. In doing so, we define the class of quasi mni matrices, containing regular mni matrices, and
we find a generalization on the number of integer extreme points adjacent to the fractional extreme point in the covering
polyhedron. We also give a relationship between the covering and stability number of regular mni matrices which allows to
prove when a regular mni matrix can be a proper minor of a quasi mni.
Partially supported by CONICET Grant PIP 2807/2000 (Argentina) and by CNPq/PROSUL Grant 490333/2004-4 (Brasil). 相似文献
90.
Four 4-hydroxyisoxazoles together with model compounds have been investigated by UV, IR and NMR spectroscopy and by pKa measurements, 4-Hydroxyisoxazoles exist predominantly in the hydroxy-form in a wide range of media. 相似文献