A versatile procedure to build high‐symmetry objects and to calculate their corresponding small‐angle scattering intensity is presented. Starting from a set of vertex positions, available from a large and extensible database, it is possible to build several types of bodies using spherical subunits. A fast implementation, based on the Debye formula using a histogram of distance, is then used to compute the theoretical scattering intensity. Since the model is built from the definition of a small set of parameters, it is possible to perform an optimization of structural parameters against experimental data. Finally, affine size polydispersities can be easily included by the rescaling of the histogram of the positions used in the calculations. Several examples of the calculations are presented, demonstrating the method and its applicability.

The structural/dynamical properties of three truncated octahedral DNA nano-cages composed by identical double helices but single strand linkers with different composition, namely 7 thymidines, 7 adenines, and 7 alternated thymidines and adenines, have been investigated through classical molecular dynamics simulations. Trajectories have been analyzed to investigate the role of the linkers in defining nano-cages stability and flexibility, including possible influence on the internal cages motions. The data indicate that the cages behavior is almost identical and that the structural/dynamical parameters measured along the trajectories are not particularly affected by the presence of different bases. These results demonstrate that the constraints imposed by the nano-structure geometry are the main factor in modulating these properties

A semiautomatic procedure to build complex atomistic covalently linked DNA nanocages has been implemented in a user-friendly, free, and fast program. As a test set, seven different truncated DNA polyhedra, composed by B-DNA double helices connected through short single-stranded linkers, have been generated. The atomistic structures, including a tetrahedron, a cube, an octahedron, a dodecahedron, a triangular prism, a pentagonal prism, and a hexagonal prism, have been probed through classical molecular dynamics and analyzed to evaluate their structural and dynamical properties and to highlight possible building faults. The analysis of the simulated trajectories also allows us to investigate the role of the different geometries in defining nanocages stability and flexibility. The data indicate that the cages are stable and that their structural and dynamical parameters measured along the trajectories are slightly affected by the different geometries. These results demonstrate that the constraints imposed by the covalent links induce an almost identical conformational variability independently of the three-dimensional geometry and that the program presented here is a reliable and valid tool to engineer DNA nanostructures.

A versatile procedure to calculate two-dimensional scattering patterns of oriented systems is presented. The systems are represented by a set of dummy atoms with different scattering length densities, which allows the construction of very complex shapes either for single particles or for sets of particles. By the use of oriented pair distance distribution functions it is possible to perform a fast calculation of the scattering intensity from the oriented system in a given direction in the scattering vector (q) space and generate the two-dimensional scattering pattern on a given q plane. Several examples of the calculations are presented, demonstrating the method and its applicability. The presented results open new possibilities for the analysis of scattering patters obtained from oriented systems.

Using Fluorescence Recovery After Photobleaching, we investigate the Brownian motion of DNA rod-like fragments in two distinct anisotropic phases with a local nematic symmetry. The height of the measurement volume ensures the averaging of the anisotropy of the in-plane diffusive motion parallel or perpendicular to the local nematic director in aligned domains. Still, as shown in using a model specifically designed to handle such a situation and predicting a non-Gaussian shape for the bleached spot as fluorescence recovery proceeds, the two distinct diffusion coefficients of the DNA particles can be retrieved from data analysis. In the first system investigated (a ternary DNA-lipid lamellar complex), the magnitude and anisotropy of the diffusion coefficient of the DNA fragments confined by the lipid bilayers are obtained for the first time. In the second, binary DNA-solvent system, the magnitude of the diffusion coefficient is found to decrease markedly as DNA concentration is increased from isotropic to cholesteric phase. In addition, the diffusion coefficient anisotropy measured within cholesteric domains in the phase coexistence region increases with concentration, and eventually reaches a high value in the cholesteric phase.

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This paper investigates whether Brazilian Central Bank communication helps to forecast the yield curve. Our forecast strategy involves two steps: First, we analyze textual Central Bank documents to extract sentiment variables that describe its communication, and then, we include those sentiment variables as additional factors into the dynamic Nelson–Siegel term structure model. We found that sentiment variables contain predictive information for yield curve forecasting. Specifically, when combined with macroeconomic variables, the sentiment variables improve the accuracy of the forecast for short maturities and forecast horizons. In addition, sentiment variables are useful in forecasting for medium and long forecast horizons for all maturities. Besides finding a new source of information to forecast the yield curve, the results indicate that the information provided by Central Bank affects market participants, proving to be a useful tool for monetary policy.

Small-angle scattering (SAS) experiments applied to nano-scaled systems allow the investigation of the constituents' overall shape, size, internal structure and arrangement. A standard scattering experiment requires a relatively simple setup and is often applied to investigate a system of particles. In these cases, the measured scattering intensity represents an average over a large number of particles illuminated by the incoming beam. The calculation and modeling of the scattering intensity can be performed by the use of analytical/semi-analytical expressions or by the use of numerical methods. In this book chapter, an overview of current available simulation/modeling methods for SAS will be shown either for systems composed of oriented or for randomly oriented particles. Examples demonstrating the use of the finite element method are presented as well as a newly developed method for calculating scattering intensity for oriented particles.