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    Identification of yttrium oxide-specific peptides for future recycling of rare earth elements from electronic scrap
    (Wiley, 2024-01-02) Maass, Danielle [UNIFESP]; Boelens, Peter; Bloss, Christoph; Claus, Gerda; Harter, Sonja; Günther, Dominik; Pollmann, Katrin; Lederer, Franziska; http://lattes.cnpq.br/3431482044015696
    Yttrium is a heavy rare earth element that acquires remarkable characteristics when it is in oxide form and doped with other rare earth elements. Owing to these characteristics Y2O3 can be used in the manufacture of several products. However, a supply deficit of this mineral is expected in the coming years, contributing to its price fluctuation. Thus, developing an efficient, cost-effective, and eco-friendly process to recover Y2O3 from secondary sources has become necessary. In this study, we used phage surface display to screen peptides with high specificity for Y2O3 particles. After three rounds of enrichment, a phage expressing the peptide TRTGCHVPRCNTLS (DM39) from the random pVIII phage peptide library Cys4 was found to bind specifically to Y2O3, being 531.6-fold more efficient than the wild-type phage. The phage DM39 contains two arginines in the polar side chains, which may have contributed to the interaction between the mineral targets. Immunofluorescence assays identified that the peptide’s affinity was strong for Y2O3 and negligible to LaPO4:Ce3+,Tb3+. The identification of a peptide with high specificity and affinity for Y2O3 provides a potentially new strategic approach to recycle this type of material from secondary sources, especially from electronic scrap.
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    Filtering for Nonlinear and Linear Markov Jump Systems
    (Alessandro Astolfi, Zhan Shu, David Castanon, 2023-10-06) Costa, Oswaldo Luiz do Valle; Oliveira, André Marcorin de; http://lattes.cnpq.br/1864836114526818
    In this paper we consider the finite horizon filtering problem of discrete-time Markov jump systems (MJS). In the first part we consider a MJS satisfying some general nonlinear conditions. It is obtained, for a fixed set of auxiliary constants, filter gains, based on a set of coupled Riccati like difference equations, that yield a minimum upper bound for the estimation error covariance matrix. When the nonlinear parameters are set to zero the MJS becomes a Markov jump linear system (MJLS) and, in the second part of the paper, it is shown that the obtained filter gains derived from a set of coupled Riccati like difference equations provide the optimal “prediction-correction” Markovian filter for the nominal MJLS (which reduces to the standard Kalman filter for the no jump case). The paper is concluded with some numerical examples © 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
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    Mixed Reduced Order Filtering for Discrete-Time Markov Jump Linear Systems with Partial Information on the Jump Parameter
    (Robert Kozma, 2023-06-21) Oliveira, André Marcorin de [UNIFESP]; Santos, Sérgio Ronaldo Barros dos [UNIFESP]; http://lattes.cnpq.br/1864836114526818
    This paper deals with the H2, H∞ and mixed H2/H∞ reduced-order filters for discrete-time Markov jump linear systems, within the context of partial observation of the jump parameter. It is considered that the Markov chain parameter, denoted by θ(k), is not observable but, instead, only an estimation, represented by ˆθ(k), is available for the filter design. Sufficient synthesis conditions for the filter design, based on linear matrix inequalities, are provided. These conditions for the H2 and H∞ filters are not conservative in the sense that, for the full-order case and perfect information of the Markov parameter, they become also necessary. Simplified conditions are derived for the Bernoulli case. The paper is concluded with an illustrative example in the context of networked control systems, in which we study the effects of reducing the order of the filter on the estimation performance.
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    Energy-to-Peak Filtering for Continuous-Time Markov Jump Linear Systems with Partial Information on the Jump Parameter
    (Amir G. Aghdam, 2023-01-10) Oliveira, André Marcorin de [UNIFESP]; Costa, Oswaldo Luiz do Valle; Gabriel, Gabriela Werner; Santos, Sérgio Ronaldo Barros dos; http://lattes.cnpq.br/1864836114526818
    In this paper, we study the L 2 −L ∞ filtering, also known as energy-to-peak filtering, for continuous-time Markov jump systems considering that the Markov chain cannot be directly measured. In this context, the filter has only access to an observed process related to the main jump process of the plant by means of an exponential hidden Markov model. Sufficient conditions for the design of full-order filters which impose the desired upper bond on the L 2 −L ∞ ratio are given in terms of Linear Matrix Inequalities. The paper is illustrated by means of a numerical example.
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    Absolute configuration reassignment of nectamazin A: Implications to related neolignans
    (Elsevier, 2023-08-21) Batista, Andrea Nastri de Luca; Santos, Carlos Henrique Totini dos; Albuquerque, Ana Carolina Ferreira de; Santos Jr, Fernando Martins dos; Garcez, Fernanda Rodrigues; Batista Jr, João Marcos [UNIFESP]; http://lattes.cnpq.br/4209224090500050
    The ability of nature to produce structurally complex molecules makes the determination of the absolute configu- ration of natural products a challenging task. Although extensive NMR analysis generally allows for the reliable assignment of relative configurations, the assignments of absolute stereochemistry are commonly performed by empirical comparisons of optical rotation (OR) and/or electronic circular dichroism (ECD) data obtained for related molecules. Such an approach, however, may lead to misassignments and consequent error propagations. Herein, we present the case of the bicyclo(3.2.1)octane neolignan named (+)-nectamazin A. This compound was first reported in 2009 from Nectandra amazonum Nees. (Lauraceae) and had its absolute configuration determined as 7R,8S,3′S,4′R,5′S by means of experimental ECD spectroscopy. Our chemical studies on Ocotea aciphylla (Lauraceae) led to the isolation of (+)-nectamazin A. The extensive analysis of OR, ECD, and vibrational CD data aided by quantum chemical cal- culations, however, indicated (+)-nectamazin A to have the 7S,8R,3′R,4′S,5′R absolute configuration, in conflict with the configuration reported in the literature. The cause of the original incorrect assignment of (+)-nectamazin A derives from the direct comparison of experimental OR and ECD data obtained for structurally related molecules with different chromophoric systems. As an alternative, VCD spectroscopy is presented as a more reliable and sensitive technique to stereochemical investigations of bicyclo(3.2.1)octane neolignans.