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URI permanent per a aquesta col·leccióhttps://hdl.handle.net/2445/104796

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Computational reconstruction of the LDL-receptor-related protein 1 (LRP1) atomistic structure evolution from super-tertiary to quaternary
(Biophysical Society, 2024) Tuveri, Gian Marco; Acosta Gutierrez, Silvia; Franzese, Giancarlo; Ruiz-Perez, Lorena; Battaglia, Giuseppe
The blood-brain barrier is a highly complex physiological barrier that separates the blood from the central nervous system to maintain the latter’s biological equilibrium. LDL receptor-related protein 1 (LRP1) is a receptor involved in BBB transcytosis and can be used by physiological or artificially induced processes. LRP1 is critical for the trafficking of misfolded proteins such as amyloid b, hyper-phosphorylated tau, and a-synuclein. Understanding its structure and function is essential to fully understanding neurological diseases like Alzheimer’s, Parkinson’s, Huntington’s, and other related dementias. LRP1 is a modular membrane protein composed of 4544 amino acids, around 1200 of which are involved in three long and flexible structures that contain coordinated calcium ions and are decorated with small sugar chains called glycans. These three flexible components are believed to have an active role in ligand binding activity and activate a peculiar and very efficient transport mechanism. No crystal structure of LRP1 is currently available. Here, we present two LRP1 conformers representing the extremes of a conformational spectrum ranging from a completely stretched, oligomer-like structure to a stable dimeric structure. The first is based on physical and biological considerations and has been built with the RoseTTAFold deep learning tool; the second conformer is obtained via homology modelling using the experimental observation of a homologous protein, LRP2, as template. We aim to assess the two conformers’ free energy variation considering the dynamics of the flexible domains obtained with atomistic molecular dynamics while rigidly fixing b-propellers’ coordinates. The obtained conformations are solvated with the BF method to estimate the species’ free energy of solvation.
Rheotaxial growth of semiconductor thin films
(Elsevier Ltd., 1987) Varela Fernández, Manuel, 1956-; Bertrán Serra, Enric; Lousa Rodríguez, Arturo; Esteve Pujol, Joan; Morenza Gil, José Luis
The efficiency of thin film solar cells depends to a large extent on the crystalline grain size. The increase of the latter can be obtained by rheotaxy, i.e. the growth of thin films on a liquid metallic layer. In this work we report the rheotaxial growth of CuInSe, thin films on liquid indium-coated glass substrates. The films were deposited onto bare glass and liquid indium coated (100 nm thickness) glass substrates by co-evaporation of copper, indium and selenium. Moreover, in order to study the influence of the indium film thickness, a deposition on a stepped indium layer with thicknesses between 10 and 100 nm was performed. The morphology, composition and crystalline properties of the deposition CuInSe, thin films have been studied in relation to the deposition parameters. The deposition rate of the rheotaxial films is much higher than that of the films deposited on glass, and increases with increasing indium layer thickness. The films are polycrystalline with grain sizes in the 0.1-0.3 pm range for films grown on glass and in the 0.332 pm range for rheotaxial films. The grain size shows an important dependence on the growth temperature and the indium layer thickness. The films grown on glass have compositions near stoichiometry, but the rheotaxial films show a higher In concentration which cannot be explained solely by the incorporation of the In layer in the growing film. The X-ray diffraction spectra indicate that the films are constituted by the crystalline phases of CuInSe, and by several binary compounds of Cu, In and Se, depending on the growth temperature. Rheotaxial films with only CuInSe, phases can be obtained by increasing the Cu flux with respect to the one used for films deposited on glass, or by decreasing the indium layer thickness.
Characterization of VGA liquid crystal panels with partial phase-only modulation: application to pattern recognition
(SPIE, 1999) Vallmitjana i Rico, Santiago; Labastida i Juan, Ignasi, 1970-; Martín Badosa, Estela; Carnicer González, Arturo; Juvells Prades, Ignacio
The inclusion of optoelectronic displays has enabled optical correlators to improve radically and maintain the competitive edge of optical processors among information processing fields. In this work, an optical correlator has been implemented by using two VGA liquid crystal displays as spatial light modulators, both at the input and Fourier planes. These devices have been removed from a commercial videoprojector and have been characterized in order to operate in different configurations. This characterization is based on an interferometric procedure which includes amplitude and phase modulation measurements. For a phase-only modulation we have compared the use of linearly and elliptically polarized light. In this latter case we have found an operating curve with phase-only modulation which takes values from 0 to π radians. This is a limitation when a pure phase filter is required as in data security and encryption, in wavelet-based systems, and in optical pattern recognition, among others. An application in this latter field is presented in our work as a solution to overcome this limited phase depth. We propose a modification of the classical phase-only filter based on the use of the absolute value of the phase. Experimental correlation results using the optical setup and the modified filter have been obtained.
Is wavefront coding an alternative to adaptive optics for retinal imaging?
(2016-07) Acosta, Eva; Arines, J.; Almaguer-Gómez, C.; Bosch i Puig, Salvador; Vallmitjana i Rico, Santiago
In this work we explore the use of the wavefront coding technique for obtaining high resolution images of the retina of human eyes. The numerical analysis pretends to show the robustness of the technique under changes in pupil diameter and wavefront shape including intersubject and intrasubject variability, using always the same restoration filter or image decoder. The results show that it is possible to obtain high resolution images under different ocular aberrations and pupil diameters with the same decoder, opening the possibility of real time high resolution images with this low-cost and robust technique.

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