Claudia Benedetti;Matteo A. C. Rossi;Matteo G. A. Paris 《Europhysics letters》2018,124(6)

We address continuous-time quantum walks on graphs in the presence of time- and space-dependent noise. Noise is modeled as generalized dynamical percolation, i.e., classical time-dependent fluctuations affecting the tunneling amplitudes of the walker. In order to illustrate the general features of the model, we review recent results on two paradigmatic examples: the dynamics of quantum walks on the line and the effects of noise on the performances of quantum spatial search on the complete and the star graph. We also discuss future perspectives, including extension to many-particle quantum walk, to noise model for on-site energies and to the analysis of different noise spectra. Finally, we address the use of quantum walks as a quantum probe to characterize defects and perturbations occurring in complex, classical and quantum, networks.https://doi.org/10.1209/0295-5075/124/60001  相似文献   

    

Claudia Redenbach  Katja Schladitz  Irene Vecchio  Oliver Wirjadi 《GAMM-Mitteilungen》2014,37(2):281-305

The development of modern high‐performance materials requires a deeper understanding of the complex relations between a material's microstructure geometry and its macroscopic properties. Analysis of three‐dimensional image data combined with stochastic microstructure modelling is a promising approach to study these relations. Motivated by two typical application examples, a fibre reinforced polymer and a closed polymer foam, we introduce versatile model classes from stochastic geometry. We explain how their basic geometric characteristics can be estimated from tomographic image data. Finally, linking the estimated values to the model parameters, stochastic models are fitted to the observed microstructures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

    

Mrcio Nele  Claudia Sayer  Jos Carlos Pinto 《Macromolecular theory and simulations》1999,8(3):199-213

The choice of appropriate reference functions is still the major drawback for collocation techniques to be used during the computation of molecular weight distributions (MWDs) in polymerization reactions and other problems constituted by systems of differential‐difference equations. Complete adaptation procedures provide significant improvement of numerical approximations obtained, but convergence to the real solution is not assured and oscillatory numerical approximations may be obtained when the actual solution experiences large variations during time integration. An alternative method to compute the reference function in an adaptative manner, called here the integration of the reference function procedure, is presented. The technique is used to allow the computation of MWDs in two polymerization problems: the metallocene‐based propene polymerization and the methyl methacrylate/butyl acrylate emulsion polymerization. The integration of the reference function procedure allowed the proper computation of broad, bimodal and fast changing distributions with polynomials of very low order (below 4), where other approximation techniques failed. The method may be easily implemented and does not require any pre‐processing before implementation.  相似文献   

    

Paolo Balma Tivola  Annamaria Deagostino  Claudia Fenoglio  Mariella Mella  Cristina Prandi  Paolo Venturello 《European journal of organic chemistry》1999,1999(9):2143-2147

Treatment of the dimethyl acetals of citral ( 1 ) and farnesal ( 2 ) with the superbase “LICKOR ” in THF at low temperatures induces regioselective metallation at the allylic methyl group at C(3). The metal–hydrogen exchange promotes immediate 1,4-elimination, yielding an (E)-configured conjugate alkyloxy-functionalized diene. The elimination product can be subjected to a Diels–Alder reaction, which allows further synthetic elaboration. In particular, in the case of farnesal dimethyl acetal the cycloaddition process leads to a derivative that can be transformed into a potential mimic agent of Juvenile hormones.  相似文献   

    

Claudia Loerbroks  Andreas Heimermann  Walter Thiel 《Journal of computational chemistry》2015,36(15):1114-1123

This article reports a combined quantum mechanics/molecular mechanics (QM/MM) investigation on the acid hydrolysis of cellulose in water using two different models, cellobiose and a 40‐unit cellulose chain. The explicitly treated solvent molecules strongly influence the conformations, intramolecular hydrogen bonds, and exoanomeric effects in these models. As these features are largely responsible for the barrier to cellulose hydrolysis, the present QM/MM results for the pathways and reaction intermediates in water are expected to be more realistic than those from a former density functional theory (DFT) study with implicit solvent (CPCM). However, in a qualitative sense, there is reasonable agreement between the DFT/CPCM and QM/MM predictions for the reaction mechanism. Differences arise mainly from specific solute–solvent hydrogen bonds that are only captured by QM/MM and not by DFT/CPCM. © 2015 Wiley Periodicals, Inc.  相似文献   

    

Claudia Bello  Shuo Wang  Lu Meng  Kelley W. Moremen  Christian F. W. Becker 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(26):7823-7828

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Béatrice Gerland;Claudia Addamiano;Brice-Loïc Renard;Corinne Payrastre;Deshmukh Gopaul;Jean-Marc Escudier; 《European journal of organic chemistry》2017,2017(11):1450-1464

Thio- and seleno-α,β- and α,β,γ-D-CNA (constrained nucleic acid) dinucleotides in which two or three torsion angles of the sugar/phosphate backbone are controlled within a dioxaphosphorinane structure have been prepared. Their structural determination was carried out by means of NMR spectroscopy to show only slight variation on the torsion-angle control in comparison with their oxo analogues. Unexpected selenium migration has been pointed out from selenophosphotriester moiety to phosphoramidite group, but this drawback can be overcome using H-phosphonate chemistry.  相似文献   

    

Claudia S. Gutsche;Benjamin F. Hohlfeld;Keith J. Flanagan;Mathias O. Senge;Nora Kulak;Arno Wiehe; 《European journal of organic chemistry》2017,2017(22):3187-3196

Boron–dipyrrins (BODIPYs) have found widespread application in bioimaging and materials science. These applications require the tuning of the chemical and photophysical properties of the fluorophore through the introduction of functional groups at the BODIPY core. In this context, an approach to difunctionalized BODIPYs was explored. Oxidative nucleophilic substitution of hydrogen (ONSH) in the 3-(α-)position of the BODIPYs was combined with nucleophilic substitution (SNAr) at the aryl unit of pentafluorophenyl-substituted BODIPYs and their dipyrrane precursors. In an alternative approach, α-alkoxy-substituted BODIPYs were prepared starting from the corresponding dipyrrin. In this case, the α-methoxy group of the BODIPY was susceptible to a hitherto unreported methoxy/amino exchange. The compounds were investigated with respect to their optical spectroscopic properties, revealing the influence of the different substitution patterns on their absorption and emission spectra.  相似文献   

    

Sara Paolella  Mariangela Bencivenni  Francesca Lambertini  Barbara Prandi  Andrea Faccini  Cinzia Tonetti  Claudia Vineis  Stefano Sforza 《Journal of mass spectrometry : JMS》2013,48(8):919-926

In the present paper, a proteomic method for species determination in fibres has been developed. Keratin was extracted from yak, wool and cashmere fibres and digested by trypsin, providing peptide mixtures that were analyzed by liquid chromatography coupled with electrospray mass spectrometry (LC/ESI‐MS) in order to identify peptidic species‐specific markers able to differentiate the fibres. Several suitable peptide markers were identified and validated in different fibres of different origin and having undergone different technological treatments, showing 100% specificity and 100% selectivity. Most of the peptide markers were also identified by means of high‐resolution mass spectrometry, confirming the origin from species‐specific keratin sequences. Some peptides were also used for the quantification of the different species in mixed fibres by LC/ESI‐MS. Validation experiments and blind tests confirmed their ability to act as very specific quantitative and qualitative markers. The method here developed is a valid complement to the standard benchmark methods for fibre identification and quantification and will be very useful for assessing the authenticity of textile products. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

    

Manuel Ávila  Claudia Vargas  Hernani Yee‐Madeira  Prof. Dr. Edilso Reguera 《无机化学与普通化学杂志》2010,636(11):1968-1973

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