scholarly journals Raman active modes in defective peapods

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Fatima Fergani ◽  
S.M. Ait Abdelkader ◽  
H. Chadli ◽  
Ah Rahmani ◽  
A. Rahmani

The vibrational properties of defective single-walled carbon nanotube filled with C60 fullerene is the subject of the current study. For this aim we use the spectral moments method in the framework of the bond-polarization theory to calculate the non-resonant Raman spectra of hexa-vacancy defective C60 peapods. Essentially, the vibrational properties are closely coupled with the atomic structure of the system. The evolution of the Raman spectrum as a function of the spatial arrangement of defects in carbon nanotubes is discussed. This work provides benchmark theoretical results to understand the experimental data of defective C60 peapods. #single_wall_carbon_nanotube #C60_peapods #hexa-vacancy_defect #Raman_spectroscopy #pectral_moment_method

2016 ◽  
Vol vol1 (1) ◽  
Author(s):  
Hassane Chadli ◽  
A. Rahmani ◽  
A. Ait Abdelkader ◽  
F. Fergani ◽  
B. Fakrach

We use the spectral moments method in the framework of the bond-polarization theory to calculate nonresonant Raman spectra of C60 peapods as a function of the concentration of fullerenes inside the single wall carbon nanotubes. The evolution of the average Raman intensity ratios between Raman mode of C60 molecules and nanotube as a function of the concentration of fullerenes has been analyzed and a general good agreement is found between calculations and measurements. #CARBON_NANOTUBES #PEAPODS #RAMAN_SPECTROSCOPY #SIMULATION #SPECTRAL_MOMENT_METHOD


2010 ◽  
Vol 27 (06) ◽  
pp. 649-667 ◽  
Author(s):  
WEI SUN ◽  
NAISHUO TIAN ◽  
SHIYONG LI

This paper, analyzes the allocation problem of customers in a discrete-time multi-server queueing system and considers two criteria for routing customers' selections: equilibrium and social optimization. As far as we know, there is no literature concerning the discrete-time multi-server models on the subject of equilibrium behaviors of customers and servers. Comparing the results of customers' distribution at the servers under the two criteria, we show that the servers used in equilibrium are no more than those used in the socially optimal outcome, that is, the individual's decision deviates from the socially preferred one. Furthermore, we also clearly show the mutative trend of several important performance measures for various values of arrival rate numerically to verify the theoretical results.


2011 ◽  
Vol 672 ◽  
pp. 358-383 ◽  
Author(s):  
NIKOS SAVVA ◽  
GRIGORIOS A. PAVLIOTIS ◽  
SERAFIM KALLIADASIS

We investigate theoretically the statistics of the equilibria of two-dimensional droplets over random topographical substrates. The substrates are appropriately represented as families of certain stationary random functions parametrized by a characteristic amplitude and wavenumber. In the limit of shallow topographies and small contact angles, a linearization about the flat-substrate equilibrium reveals that the droplet footprint is adequately approximated by a zero-mean, normally distributed random variable. The theoretical analysis of the statistics of droplet shift along the substrate is highly non-trivial. However, for weakly asymmetric substrates it can be shown analytically that the droplet shift approaches a Cauchy random variable; for fully asymmetric substrates its probability density is obtained via Padé approximants. Generalization to arbitrary stationary random functions does not change qualitatively the behaviour of the statistics with respect to the characteristic amplitude and wavenumber of the substrate. Our theoretical results are verified by numerical experiments, which also suggest that on average a random substrate neither enhances nor reduces droplet wetting. To address the question of the influence of substrate roughness on wetting, a stability analysis of the equilibria must be performed so that we can distinguish between stable and unstable equilibria, which in turn requires modelling the dynamics. This is the subject of Part 2 of this study.


2014 ◽  
Vol 33 (2) ◽  
pp. 83 ◽  
Author(s):  
Federico Camerlenghi ◽  
Vincenzo Capasso ◽  
Elena Villa

Many real phenomena may be modelled as random closed sets in ℝd, of different Hausdorff dimensions. The problem of the estimation of pointwise mean densities of absolutely continuous, and spatially inhomogeneous, random sets with Hausdorff dimension n < d, has been the subject of extended mathematical analysis by the authors. In particular, two different kinds of estimators have been recently proposed, the first one is based on the notion of Minkowski content, the second one is a kernel-type estimator generalizing the well-known kernel density estimator for random variables. The specific aim of the present paper is to validate the theoretical results on statistical properties of those estimators by numerical experiments. We provide a set of simulations which illustrates their valuable properties via typical examples of lower dimensional random sets.


ChemPhysChem ◽  
2006 ◽  
Vol 7 (2) ◽  
pp. 342-344 ◽  
Author(s):  
Alessandro Damin ◽  
Francesca Bonino ◽  
Silvia Bordiga ◽  
Elena Groppo ◽  
Carlo Lamberti ◽  
...  

2018 ◽  
Vol 28 (2) ◽  
pp. 5-17 ◽  
Author(s):  
Adam Bujarkiewicz ◽  
Jarosław Gajewski ◽  
Tomasz Janiak ◽  
Justyna Sobczak-Piąstka ◽  
Jacek Sztubecki ◽  
...  

Abstract The subject of the research is a footbridge across the river Brda in Bydgoszcz. The measurements of the footbridge displacements with the test load were undertaken. The paper presents the results of the measurements and compares them with the theoretical results obtained using the finite element method (FEM). On this basis, discrepancy between actual work of the structure and numerical simulations was found. Attempt to explain the reasons for the observed differences and direction of further research were included in the conclusions.


2021 ◽  
Vol 1203 (2) ◽  
pp. 022030
Author(s):  
Weronika Skowronek ◽  
Dorota Winnicka-Jasłowska

Abstract This article concerns the design and architecture of educational facilities in Poland. It presents selected architectural and spatial solutions for modern primary school buildings. The article is based on a juxtaposition of two school buildings built in the second decade of the 21st century, located in the central and southern part of the country. Contemporary buildings were selected to draw attention to the changing approach to design and the development of architecture dedicated to the youngest recipients, emphasizing important aspects of the school space in the era of growing demands and social awareness. The analysis of the buildings indicated in the article was carried out on the basis of the available literature on the subject, comparison with typical buildings in Poland, and in situ research in school buildings, with an emphasis on the key aspects of the functional and spatial arrangement in the presented facilities, determining the target educational space for students. A school building in Poland, in the minds of many architecture recipients, is associated with a typical building, such as 'millennial schools', created as part of the campaign to build a thousand schools - monuments related to the celebration of the Millennium of the Polish State. The typification period, abounding in many buildings that still function to this day, lasted almost twenty years until 1981, when the standard for typical schools was repealed. At that time, the search for the perfect form of the building as well as flexible and functional school spaces, tailored to the scale of the youngest recipients, began. The classroom, which used to be the only condition for the functioning of the school, turned out to be insufficient. Modern projects have started to be implemented, which systematically contribute to the creation of a new image of the school as a friendly and modern institution, maintained in an optimal and holistic development-oriented educational environment.


2018 ◽  
Vol 20 (48) ◽  
pp. 30174-30188 ◽  
Author(s):  
Andreas Brinkmann ◽  
Ulrich Sternberg ◽  
Petra H. M. Bovee-Geurts ◽  
Isabelle Fernández Fernández ◽  
Johan Lugtenburg ◽  
...  

19F solid-state NMR studies together with bond polarization theory chemical shift tensor calculations provide insight into the chromophore of rhodopsin and its active state Meta II.


Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4417 ◽  
Author(s):  
Christophe Farès ◽  
Julia B. Lingnau ◽  
Cornelia Wirtz ◽  
Ulrich Sternberg

The downscaling of NMR tensorial interactions, such as dipolar couplings, from tens of kilohertz to a few hertz in low-order media is the result of dynamics spanning several orders of magnitudes, including vibrational modes (~ns-fs), whole-molecule reorientation (~ns) and higher barrier internal conformational exchange (<ms). In this work, we propose to employ these dynamically averaged interactions to drive an “alignment-tensor-free” molecular dynamic simulation with orientation constraints (MDOC) in order to efficiently access the conformational space sampled by flexible small molecules such as natural products. Key to this approach is the application of tensorial pseudo-force restraints which simultaneously guide the overall reorientation and conformational fluctuations based on defined memory function over the running trajectory. With the molecular mechanics force-field, which includes bond polarization theory (BPT), and complemented with other available NMR parameters such as NOEs and scalar J-couplings, MDOC efficiently arrives at dynamic ensembles that reproduce the entire NMR dataset with exquisite accuracy and theoretically reveal the systems conformational space and equilibrium. The method as well as its potential towards configurational elucidation is presented on diastereomeric pairs of flexible molecules: a small 1,4-diketone 1 with a single rotatable bond as well as a 24-ring macrolide related to the natural product mandelalide A 2.


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