Search results for "Note"
showing 10 items of 10709 documents
Heptane adsorption in silicalite-1 : molecular dynamics simulation.
2009
Molecular dynamics (MD) simulations have been used to study the adsorption process of n-heptane molecules in silicalite-1 at 300 K. MD simulated results were compared to experimental neutron diffraction (ND) and experimental self-diffusion coefficients. The analysis of MD data indicated a packing of the adsorbed molecules around 4 mol./u.c., which is not the consequence of an enthalpic effect but of an entropic effect. The role of the n-heptane chain flexibility (cis–trans conformation) in relation with the silicalite-1 channel type (straight versus sinusoidal) was outlined and enabled to understand the mobility change arising at 4 mol./u.c., according to previous experimental results. The …
Engineering 3D ordered molecular thin films by a nanoscale control
2010
This perspective aims to report on experimental preparation and investigation tools for engineering molecular thin films with a three-dimensional (3D) nanoscale control that is of relevant interest for different emerging applications as well as for the development of calibration standards. Such thin films may be obtained by man-made methods, self-assembly or spatio-temporal self-organization and/or by the combination of these last approaches with external tools. Understanding the main features and the physical-chemistry underlying the related ordering phenomena is in due course and a theoretical framework is under development. In this respect it is of fundamental importance to achieve the a…
Resonant laser spectroscopy of localized excitons in monolayer WSe_2
2016
Coherent quantum control and resonance fluorescence of few-level quantum systems is integral for quantum technologies. Here we perform resonance and near-resonance excitation of three-dimensionally confined excitons in monolayer WSe2 to reveal near-ideal single-photon fluorescence with count rates up to 3 MHz. Using high-resolution photoluminescence excitation spectroscopy of the localized excitons, we uncover a weakly fluorescent exciton state ∼5 meV blue shifted from the ground-state exciton, providing important information to unravel the precise nature of quantum states. Successful demonstration of resonance fluorescence paves the way to probe the localized exciton coherence in two-dime…
Characterization of single semiconductor nanowires by synchrotron radiation nanoprobe
2012
In this work, we report on the results of the characterization of single semiconductor nanowires by x-ray fluorescence nanoprobe. Wurtzite InGaN and Co-implanted ZnO single nanowires were studied. Ternary semiconductor nanowires show an axial inhomogeneous elemental distribution, with Ga accumulating at the bottom and In at the top of the wires. The ZnO NWs, on the other hand, show a homogeneous distribution of the Co implanted along the nanowires, without signatures of clustering or segregation effects induced by the implantation. No signatures of unintentional doping are observed neither in the InGaN nor the ZnO NWs. These overall results demonstrate the suitability of X-ray fluorescence …
Spectral and temporal distribution of biomolecules by Dynamic SERS
2014
In this thesis, the definition of SERS as a biosensor has been tested and a new approach developed for. Also, in terms of quantification, it has been shown that SERS can be an efficient tool. Concerning the selectivity, the spectral quality was improved. A low limit of detection associated to the statistical and dynamic approach allows a very good sensitivity (under the nanomolar). This approach also enables a high reproducibility in time of the sensor. Thus, as low as SERS does not well answer to the sensor capabilities in a classical approach, in our case the coupling between a non-functionalized GNPs substrate coupled with a microfluidic chip, all mounted on a confocal microscope for tem…
A voltammetric e-tongue tool for the emulation of the sensorial analysis and the discrimination of vegetal milks
2018
[EN] The relevance of plant-based food alternatives to dairy products, such as vegetable milks, has been growing in recent decades, and the development of systems capable of classifying and predicting the sensorial profile of such products is interesting. In this context, a methodology to perform the sensorial analysis of vegetable milks (oat, soya, rice, almond and tiger nut), based on 12 parameters, was validated. An electronic tongue based on the combination of eight metals with pulse voltammetry was also tested. The current intensity profiles are characteristic for each non-dairy milk type. Data were processed with qualitative (PCA, dendrogram) and quantitative (PLS) tools. The PCA stat…
A closed-form solution for natural frequencies of thin-walled cylinders with clamped edges
2016
Abstract This paper presents an approximate closed-form solution for the free-vibration problem of thin-walled clamped–clamped cylinders. The used indefinite equations of motion are classic. They derive from Reissner׳s version of Love׳s theory, properly modified with Donnell׳s assumptions, but an innovative approach has been used to find the equations of natural frequencies, based on a solving technique similar to Rayleigh׳s method, on the Hamilton׳s principle and on a proper constructions of the eigenfuctions. Thanks to the used approach, given the geometric and mechanical characteristics of the cylinder, the model provides the natural frequencies via a sequence of explicit algebraic equat…
Computation and Display of 3D Movie From a Single Integral Photography
2016
Integral photography is an auto-stereoscopic technique that allows, among other interesting applications, the display of 3D images with full parallax and avoids the painful effects of the accommodation-convergence conflict. Currently, one of the main drawbacks of this technology is the need of a huge amount of data, which have to be stored and transmitted. This is due to the fact that behind every visual resolution unit, i.e. behind any microlens of an integral-photography monitor, between 100 and 300 pixels should appear. In this paper, we make use of an updated version of our algorithm, SPOC 2.0, to alleviate this situation. We propose the application of SPOC 2.0 for the calculation of co…
A single-domain Ritz approach for buckling and post-buckling analysis of cracked plates
2019
Abstract A Ritz approach for the analysis of buckling and post-buckling of plates with through-the-thickness cracks is presented. The plate behavior is described by the first order shear deformation theory and von Karman’s geometric nonlinearity. The admissible functions used in the displacements approximation are series of regular orthogonal polynomial supplemented with special functions able to decribe the dicontinuity across the crack and the singularity at the crack tips; boundary functions are used to fullfill the homogeneous essential boundary conditions. Convergence studies and analysis results are presented for buckling and post-buckling of plates with a central through-the-thicknes…
ChemInform Abstract: Multiple 1,2,3-Thiadiazoles.
2010
A series of compounds 3a-d,i-n with two or three 1,2,3-thiadiazole rings, useful for photocrosslinking processes, was prepared from the di- or triketones 1a-d,i-n via the corresponding hydrazones 2a-d,i-n by applying the Hurd-Mori method. A special synthetic sequence, 1e, 2e, 3e, 3f/3g, was elaborated for the olefinic system 3h.