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[Hypothesis] The internal organization of polyelectrolyte layers deposited on colloidal templates plays a very important role for the potential applications of these systems as capsules for drug delivery purposes., [Experiments] The mutual arrangement of oppositely charged polyelectrolyte layers upon their deposition on positively charged liposomes has been studied by combining up three different scattering techniques and Electronic Spin Resonance, which has provided information about the inter-layer interactions and their effect on the final structure of the capsules., [Findings] The sequential deposition of oppositely charged polyelectrolytes on the external leaflet of positively charged liposomes allows modulating the organization of the obtained supramolecular structures, impacting the packing and rigidity of the obtained capsules due to the change of the ionic cross-linking of the multi-layered film as a result of the specific charge of the last deposited layer. The possibility to modulate the properties of the LbL capsules by tuning the characteristics of the last deposited layers offers a very interesting route for the design of materials for encapsulation purposes with their properties controlled almost at will by changing the number of deposited layers and their chemistry.

A numerical method to detect objects buried in a medium by surface thermal measurements is presented. We propose a new approach combining the use of topological derivatives and Laplace transforms. The original optimization problem with time-dependent constraints is replaced by an equivalent problem with stationary constraints by means of Laplace transforms. The first step in the reconstruction scheme consists in discretizing the inversion formula to produce an approximate optimization problem with a finite set of constraints. Then, an explicit expression for the topological derivative of the approximate shape functional is given. This formula is evaluated at low cost using explicit expressions of the forward and adjoint fields involved. We apply this technique to a simple shape reconstruction problem set in a half space. Good approximations of the number, location and size of the obstacles are obtained. The description of their shapes can be improved by more expensive hybrid methods combining time averaging with topological derivative based iterative schemes., MEC/FEDER, Depto. de Análisis Matemático y Matemática Aplicada, Fac. de Ciencias Matemáticas, TRUE, pub

Submitted: November 20, 2014. Final revision submitted: March 20, 2015. Accepted: March 22, 2015., Purpose To examine the capacity of straylight and disk halo size to diagnose cataract. Setting Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain. Design Prospective study. Methods Straylight, disk halo radius, and high-contrast corrected distance visual acuity (CDVA) measurements were compared between patients with age-related cataract and age-matched normal-sighted control subjects by calculating the area under the curve (AUC) receiver operating characteristic. Results Measurements were made in 53 eyes of 53 patients with a mean age of 67.94 years ± 7.11 (SD) and 31 eyes of 31 controls with a mean age 66.06 ± 5.43 years. Significantly worse (P <.001) mean straylight (1.38 ± 0.24 log[s]), mean disk halo radius (2.40 ± 0.18 log minutes of arc [arcmin]), and mean CDVA (0.17 ± 0.11 logMAR) were recorded in the cataract group than in the control group (1.17 ± 0.11 log[s], 2.10 ± 0.16 log arcmin, and 0.08 ± 0.08 logMAR). Significant differences in AUCs were observed for disk halo radius (0.89 ± 0.04) versus straylight (0.77 ± 0.05) (P =.03) and disk halo radius versus CDVA (0.72 ± 0.05) (P =.001). The comparison of disk halo radius versus the discriminant function with input from CDVA and straylight (0.80 ± 0.05) was at the limit of significance only (0.091 ± 0.05, P =.051). Conclusion Although all 3 variables discriminated well between normal eyes and eyes with cataract, the disk halo radius showed the best diagnostic capacity. Financial Disclosure Neither author has a financial or proprietary interest in any material or method mentioned., Industrias de Optica Prats S.L, Depto. de Optometría y Visión, Fac. de Óptica y Optometría, TRUE, pub

Es una versión postprint., The far-field scattered in the infrared by an arrangement of metallic structures deposited on a dielectric wafer is estimated in this paper. The scattering is modelled by using operators that describe the far field obtained under the regime applicable for the Babinet's principle in its vectorial approach and the Stratton–Chu approximation. The far-field scattered by an arrangement of thin gold layers over a dielectric wafer under infrared illumination is computed. The model assumes a normally incident vectorial Gaussian beam focused over the arrangement plane. An angular spectrum decomposition of the field is done. Then, every plane wave is scattered by the whole structure: arrangement + substrate layer. The reflexions in the substrate layer and the arrangement action have been taken into account in an operator formalism. Numerical results estimating the influence of substrate thickness on the pattern are obtained., Ministerio de Ciencia y Tecnologı́a de España, Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

In this paper, numerical simulations are conducted to study elastic wave transport, scattering, and attenuation in a naturally fractured rock associated with length-correlated fracture normal and shear stiffnesses. The model represents the pattern of a real fracture outcrop in an explicit fashion based on the discrete fracture network approach and computes the dynamical interaction between waves and fractures based on the displacement discontinuity method. A broad spectrum of geologically relevant fracture stiffness values are explored to analyse the impact of fracture normal and shear stiffness components on the wavefield evolution. It is observed that when the fracture normal and shear stiffnesses are both high, the wavefield is a propagative mode dominated by a forward ballistic transport. With the reduction of fracture normal and/or shear stiffnesses, the wavefield becomes diffusive characterised by the emergence and dominance of coda waves. If the fracture stiffnesses are very low, waves become trapped entering the so-called localisation regime associated with an absence of effective transport as well as a profound attenuation. Our results show that the scattering attenuation of S waves tends to be greater than that of P waves in the propagation and diffusion regimes, but becomes similar in the localisation regime. The research findings of this paper have important implications for understanding and predicting the seismic wave attenuation behaviour in naturally fractured rocks for various geophysical applications.

In this work, pectin extracts from watermelon rind (WRP) were enzymatically treated to evaluate their potential for preparing hydrogels with the addition of CaCl2. Based on a previous work, two different conditions were selected to obtain WRP extracts according to the 1) highest yield (OP) or 2) highest yield without negatively affecting the branching and native structure of pectin (OPA). Firstly, both WRP extracts were enzymatically modified using different treatments (de-esterification and/or de-branching of galacturonic and arabinose side chains, and deproteinization), and their impact on the esterification degree, monosaccharide composition and changes on their structural properties (linearity and branching degree) were analysed. Then, the effect of the structural properties of the resulting pectin on the rheological behaviour and nanostructure of the hydrogels was investigated. The presence of long branched side chains and high methyl-esterified galacturonic acid chains promoted the formation of weaker hydrogels whereas de-esterification of the original pectin enabled intermolecular association giving rise to stronger hydrogels with the formation of ordered and densely packed structures (as deduced from SAXS results). However, the presence of small arabinogalactans side chains in the de-branched and de-esterified pectin extracts acted as reinforcement agents, inducing the formation of more densely packed networks and stronger hydrogels than their less-branched counterpart. These results demonstrated the impact of the pectin structure on the hydrogel-forming capacity.

In this paper, numerical simulations are conducted to study elastic wave transport, scattering, and attenuation in a naturally fractured rock associated with length-correlated fracture normal and shear stiffnesses. The model represents the pattern of a real fracture outcrop in an explicit fashion based on the discrete fracture network approach and computes the dynamical interaction between waves and fractures based on the displacement discontinuity method. A broad spectrum of geologically relevant fracture stiffness values are explored to analyse the impact of fracture normal and shear stiffness components on the wavefield evolution. It is observed that when the fracture normal and shear stiffnesses are both high, the wavefield is a propagative mode dominated by a forward ballistic transport. With the reduction of fracture normal and/or shear stiffnesses, the wavefield becomes diffusive characterised by the emergence and dominance of coda waves. If the fracture stiffnesses are very low, waves become trapped entering the so-called localisation regime associated with an absence of effective transport as well as a profound attenuation. Our results show that the scattering attenuation of S waves tends to be greater than that of P waves in the propagation and diffusion regimes, but becomes similar in the localisation regime. The research findings of this paper have important implications for understanding and predicting the seismic wave attenuation behaviour in naturally fractured rocks for various geophysical applications.

In this paper, numerical simulations are conducted to study elastic wave transport, scattering, and attenuation in a naturally fractured rock associated with length-correlated fracture normal and shear stiffnesses. The model represents the pattern of a real fracture outcrop in an explicit fashion based on the discrete fracture network approach and computes the dynamical interaction between waves and fractures based on the displacement discontinuity method. A broad spectrum of geologically relevant fracture stiffness values are explored to analyse the impact of fracture normal and shear stiffness components on the wavefield evolution. It is observed that when the fracture normal and shear stiffnesses are both high, the wavefield is a propagative mode dominated by a forward ballistic transport. With the reduction of fracture normal and/or shear stiffnesses, the wavefield becomes diffusive characterised by the emergence and dominance of coda waves. If the fracture stiffnesses are very low, waves become trapped entering the so-called localisation regime associated with an absence of effective transport as well as a profound attenuation. Our results show that the scattering attenuation of S waves tends to be greater than that of P waves in the propagation and diffusion regimes, but becomes similar in the localisation regime. The research findings of this paper have important implications for understanding and predicting the seismic wave attenuation behaviour in naturally fractured rocks for various geophysical applications.

In this paper, numerical simulations are conducted to study elastic wave transport, scattering, and attenuation in a naturally fractured rock associated with length-correlated fracture normal and shear stiffnesses. The model represents the pattern of a real fracture outcrop in an explicit fashion based on the discrete fracture network approach and computes the dynamical interaction between waves and fractures based on the displacement discontinuity method. A broad spectrum of geologically relevant fracture stiffness values are explored to analyse the impact of fracture normal and shear stiffness components on the wavefield evolution. It is observed that when the fracture normal and shear stiffnesses are both high, the wavefield is a propagative mode dominated by a forward ballistic transport. With the reduction of fracture normal and/or shear stiffnesses, the wavefield becomes diffusive characterised by the emergence and dominance of coda waves. If the fracture stiffnesses are very low, waves become trapped entering the so-called localisation regime associated with an absence of effective transport as well as a profound attenuation. Our results show that the scattering attenuation of S waves tends to be greater than that of P waves in the propagation and diffusion regimes, but becomes similar in the localisation regime. The research findings of this paper have important implications for understanding and predicting the seismic wave attenuation behaviour in naturally fractured rocks for various geophysical applications.

In this paper, numerical simulations are conducted to study elastic wave transport, scattering, and attenuation in a naturally fractured rock associated with length-correlated fracture normal and shear stiffnesses. The model represents the pattern of a real fracture outcrop in an explicit fashion based on the discrete fracture network approach and computes the dynamical interaction between waves and fractures based on the displacement discontinuity method. A broad spectrum of geologically relevant fracture stiffness values are explored to analyse the impact of fracture normal and shear stiffness components on the wavefield evolution. It is observed that when the fracture normal and shear stiffnesses are both high, the wavefield is a propagative mode dominated by a forward ballistic transport. With the reduction of fracture normal and/or shear stiffnesses, the wavefield becomes diffusive characterised by the emergence and dominance of coda waves. If the fracture stiffnesses are very low, waves become trapped entering the so-called localisation regime associated with an absence of effective transport as well as a profound attenuation. Our results show that the scattering attenuation of S waves tends to be greater than that of P waves in the propagation and diffusion regimes, but becomes similar in the localisation regime. The research findings of this paper have important implications for understanding and predicting the seismic wave attenuation behaviour in naturally fractured rocks for various geophysical applications.

Erosion of microplastics due to residence time in aquatic environments causes roughening of the microplastic. Unfortunately, currently used measurement methods do not provide information on the surface roughness of the microplastic embedded in water. In this study we propose a novel method by using transmittance to get information on the magnitude of the surface roughness of microplastics and to rank microplastics by thickness. For such a purpose, we studied optical properties such as dispersion, absorption of both plastics and water in the partial spectral range of visible light (Vis), transmission and scattering of light by plastic sheets, as well as, the calculated sample thickness in the Vis region. These were explored for the detection of both smooth and roughened plastic sheets immersed in water. Moreover, by using the transmission spectrum and refractive index of both plastic and water it is possible to estimate the average surface roughness of plastic samples. Our results suggest that the optical properties in the Vis region offer an interesting way for the detection of both rough and smooth plastic sheets and for ranking the type of plastics in an aquatic environment.

The action of the enzyme CGTase on corn and potato starch was studied to understand the influence of starch structure and cyclodextrin (CD) production. Native and hydrolysed materials were analysed using multiple characterisation methods enabling coverage over more than six orders of magnitude in length-scale. The production of CD was greater for corn than potato but the relative abundance between different CD molecules was conserved. Structural differences were observed for all length scales investigated as a result of hydrolysis but to different extents between the starches. These observations were explained by differing modes of enzymatic attack between starch varieties. In corn, surface pores facilitated action of CGTase with hydrolysis generating limited changes in crystallinity and surface granule order. Hydrolysis of potato starch resulted in erosion at the granule surface, increase in surface order and overall crystallinity. Hydrolysis had minimal effect on the gelatinisation behaviour of both starches. Changes in the small-angle scattering due to CGTase confirmed the different mode of action of the enzyme between the two starches. Following hydrolysis, these changes in corn were consistent with preferential attack of the amorphous lamellae, while in potato, preferential hydrolysis of amorphous growth rings was indicated. These findings provide new insight into this industrially relevant enzyme and will assist in the optimisation of CGTase-based processing conditions for the development of novel products.

This paper presents the results of an analysis of the low-energy differential cross sections, acquired by the CHAOS Collaboration at TRIUMF. We first analyse separately the π+p and the π−p elastic-scattering measurements on the basis of standard low-energy parameterisations of the s- and p-wave K-matrix elements. After the removal of the outliers, we subject the truncated π±p elastic-scattering databases into a common optimisation scheme using the ETH model; the optimisation failed to produce reasonable values for the model parameters. We conclude that the problems we have encountered in the analysis of these data are due to the shape of the angular distributions of their π+p differential cross sections.

A set of the Classic and official Jun ware shards found at various kilns at Yuzhou (Henan) are analyzed. The blue color and milky appearance of the glazes subject of intense debate as being due to either the glaze nanostructure or chemistry. The presence of submillimetre areas showing different color and opacity gives to the glazes a three dimensional cloudy sky appearance. Nanostructure and chemistry of the glazes, oxidation state of iron and nature of the copper nanoprecipitates are studied at a submillimetre level. Images of the glaze nanostructures are obtained using a Focus Ion Beam and Scanning Electron Microscope with nanometric resolution. The size and volume fraction of the nanostructures determined by image treatment are related to the chemical composition of the glazes. Differences between kiln productions are found and the origin of the color and opacity of the glazes discussed in terms of the chemistry and nanostructure., Peer Reviewed, Postprint (author's final draft)

Great success has been achieved in the modeling of gas-surface elementary processes by the use of the Born-Oppenheimer approximation. However, in metal surfaces low energy electronic excitations are generated even by thermal and hyperthermal molecules due to the absence of band gaps in the electronic structure. This shows the importance of performing dynamical simulations that incorporate non-adiabatic effects to analyze in which way they affect most common gas-surface reactions. Here we review recent theoretical developments in this problem and their application to the study of the effect of electronic excitations in the adsorption and relaxation of atoms and molecules in metal surfaces, in scattering processes, and also in recombinative processes between impinging atoms and adsorbates at the surface. All these studies serve us to establish what properties of the gas-surface interaction favor the excitation of low-energy electron-hole pairs. A general observation is that the nature of these excitations usually requires long lasting interactions at the surface in order to observe deviations from the adiabatic behaviour. We also provide the basis of the local density friction approximation (LDFA) that have been used in all these studies, and show how it has been employed to perform ab initio molecular dynamics with electronic friction (AIMDEF). As a final remark, we will shortly review on recent applications of the LDFA to successfully simulate desorption processes induced by intense femtosecond laser pulses.

We present the derivation of the two-loop gluon Regge trajectory using Lipatov's high energy effective action and a direct evaluation of Feynman diagrams. Using a gauge invariant regularization of high energy divergences by deforming the light-cone vectors of the effective action, we determine the two-loop self-energy of the reggeized gluon, after computing the master integrals involved using the Mellin-Barnes representations technique. The self-energy is further matched to QCD through a recently proposed subtraction prescription. The Regge trajectory of the gluon is then defined through renormalization of the reggeized gluon propagator with respect to high energy divergences. Our result is in agreement with previous computations in the literature, providing a non-trivial test of the effective action and the proposed subtraction and renormalization framework.

The scattering of terahertz radiation on a graphene-based nano-patch antenna is numerically analyzed. The extinction cross section of the nano-antenna supported by silicon and silicon dioxide substrates of different thickness are calculated. Scattering resonances in the terahertz band are identified as Fabry–Perot resonances of surface plasmon polaritons supported by the graphene film. A strong tunability of the antenna resonances via electrostatic bias is numerically demonstrated, opening perspectives to design tunable graphene-based nano-antennas. These antennas are envisaged to enable wireless communications at the nanoscale., Peer Reviewed, Postprint (published version)

[EN] In order to identify the type of scattering profile that corresponds to some specific shapes, we have performed calculations of some scattering properties for those shapes with a fixed size distribution. Aggregates of different numbers of spheres have been used to fit the laboratory measurements of fly ashes. The results for other shapes, such as rectangular prisms with different axial proportions, particles made of joined cubes, and particles with different fluffiness, are also shown. From all these calculations, it is concluded that the size-averaged scattering matrix elements resembles Rayleigh features, for the size distribution stopping at 1.0¿m, when either the number of spheres or cubes of the aggregates is increased, the shape becomes flatter or the particles become fluffier. We also show the effect of the refractive index on the Qsca vs. X curve in the case of strongly absorbing particles. A tendency to reach the geometric optic regime is observed instead of the Rayleigh regime using the same size distribution. © 2011 Elsevier Ltd.

The use of spectrophotometers for the measurement of cell concentration in yeast suspension is critically discussed. Corrections are derived which take into account cell size, shape, cell aggregation (flocculation) and non linear effects related to sample thickness (cell piling)

We report an ab initio calculation of the adiabatic electronic properties of He and Ne atoms interacting with a jellium (Al-like) surface, in the framework of the embedding method and using density functional theory in the local density approximation. In particular, attention is focused on the repulsive atom-surface potential. For incident atoms with initial kinetic energies in the typical experimental range (up to about 200 meV), it is shown that Ne gets closer to the metal than He. This is in agreement with the experimental observation of a greater sensitivity to the surface electronic structure of Ne than of He, but in contrast with results obtained by simply applying the effective medium theory to the Ne/metal system.

[EN] We have studied the gammap--> pi+ pi- p reaction using a model which includes N, DELTA(1232), N*(1440) and N*(1520) intermediate baryonic states and the rho-meson as intermediate 2pi-resonance. The model reproduces fairly well experimental cross sections below E(gamma) = 800 MeV and invariant-mass distributions even at higher energies. One of the interesting findings of the study is that the gammaN --> N* (1520) --> DELTApi process is very important and interferes strongly with the dominant DELTA Kroll-Ruderman term to produce the experimental peak of the cross section. We show that the study of the reaction can provide information on some couplings, concretely the N*(1520) --> DELTApi. We also find that the pion energy distributions for different photon energies, which have not been measured so far, contain very valuable information on the dynamics of the reaction. Finally, the analogies and differences with respect to the piN --> 2piN reaction are also discussed.

[EN] We have studied the gammap--> pi+ pi- p reaction using a model which includes N, DELTA(1232), N*(1440) and N*(1520) intermediate baryonic states and the rho-meson as intermediate 2pi-resonance. The model reproduces fairly well experimental cross sections below E(gamma) = 800 MeV and invariant-mass distributions even at higher energies. One of the interesting findings of the study is that the gammaN --> N* (1520) --> DELTApi process is very important and interferes strongly with the dominant DELTA Kroll-Ruderman term to produce the experimental peak of the cross section. We show that the study of the reaction can provide information on some couplings, concretely the N*(1520) --> DELTApi. We also find that the pion energy distributions for different photon energies, which have not been measured so far, contain very valuable information on the dynamics of the reaction. Finally, the analogies and differences with respect to the piN --> 2piN reaction are also discussed.