An implementation of optimal control methods (LQI, LQG, LTR) for geostationary satellite attitude control

This paper investigates a new strategy for geostationary satellite attitude control using Linear Quadratic Gaussian (LQG), Loop Transfer Recovery (LTR), and Linear Quadratic Integral (LQI) control techniques. The sub-system satellite attitude determination and control of a geostationary satellite in the presence of external disturbances, the dynamic model of sub-satellite motion is firstly established by Euler equations. During the flight mission at 35000 Km attitude, the stability characteristics of attitude motion are analyzed with a large margin error of pointing, then a height performance-order LQI, LQG and LTR attitude controller are proposed to achieve stable control of the sub-satellite attitude, which dynamic model is linearized by using feedback linearization method. Finally, validity of the LTR order controller and the advantages over an integer order controller are examined by numerical simulation. Comparing with the corresponding integer order controller (LQI, LQG), numerical simulation results indicate that the proposed sub-satellite attitude controller based on LTR order can not only stabilize the sub-satellite attitude, but also respond faster with smaller overshoot.

Facile preparation of CuBi2O4/TiO2 hetero-systems employed for simulated solar-light selective oxidation of 4-methoxybenzyl alcohol model compound

The selective photocatalytic oxidation of organic substances is today considered one of the green techniques to synthesize important starting materials in different technological applications. This work reports an efficient, simple and cheap strategy for the synthesis of a new photocatalytic CuBi2O4-TiO2 (CBO/TiO2) heterosystem at room temperature. The prepared powders were characterized by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectra (DRS), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The photocatalytic activity was evaluated by performing a probe reaction, namely the partial oxidation of 4-methoxybenzyl alcohol (4-MBA) to 4-methoxybenzaldehyde (4-MBAld) in aqueous solution under irradiation of simulated sunlight. The CBO/TiO2 coupled systems showed a higher photoactivity than the single photocatalysts reaching a selectivity of 45% towards 4‑methoxy-benzaldehyde with an alcohol conversion of 77% after 4 h of irradiation. Furthermore, although a high alcohol conversion was achieved, the selectivity towards 4-MBAld was significant, unlike what has been reported in the literature for many heterogeneous photocatalytic reactions whose selectivity generally decreases significantly with the increasing conversion of the starting alcohol molecule. The improved photocatalytic activity could be attributed to the partial coverage of the TiO2 surface by CBO which reduces the subsequent oxidation of the formed aldehyde

BET Inhibition-Induced GSK3β Feedback Enhances Lymphoma Vulnerability to PI3K Inhibitors

The phosphatidylinositol 3 kinase (PI3K)-glycogen synthase kinase \u3b2 (GSK3\u3b2) axis plays a central role in MYC-driven lymphomagenesis, and MYC targeting with bromodomain and extraterminal protein family inhibitors (BETi) is a promising treatment strategy in lymphoma. In a high-throughput combinatorial drug screening experiment, BETi enhance the antiproliferative effects of PI3K inhibitors in a panel of diffuse large B cell lymphoma (DLBCL) and Burkitt lymphoma cell lines. BETi or MYC silencing upregulates several PI3K pathway genes and induces GSK3\u3b2 S9 inhibitory phosphorylation, resulting in increased \u3b2-catenin protein abundance. Furthermore, BETi or MYC silencing increases GSK3\u3b2 S9 phosphorylation levels and \u3b2-catenin protein abundance through downregulating the E2 ubiquitin conjugating enzymes UBE2C and UBE2T. In a mouse xenograft DLBCL model, BETi decrease MYC, UBE2C, and UBE2T and increase phospho-GSK3\u3b2 S9 levels, enhancing the anti-proliferative effect of PI3K inhibitors. Our study reveals prosurvival feedbacks induced by BETi involving GSK3\u3b2 regulation, providing a mechanistic rationale for combination strategies. In this study, Derenzini et al. demonstrate that BET inhibitors enhance lymphoma vulnerability to PI3K inhibitors by inducing GSK3\u3b2 feedback in a MYC-dependent manner and by downregulating E2-ubiquitin conjugating enzymes, which further enhance the feedback. These data provide the rationale for combining BET and PI3K inhibitors in lymphoma therapy

A study of the phase transitions, electronic structures and thermodynamic properties of Mg2X (X = Ge, Si and Sn) under high pressure

In this work, we theoretically investigate phase transitions, electronic structures and thermodynamic properties of Mg2X (X = Ge, Si and Sn) under high pressures. To reach this goal, the total energy has been calculated by using the full-potential linearized augmented plane wave (FP-LAPW) method with generalized gradient approximation (GGA), local density approximation (LDA) and Engel–Vosko approximation (EV-GGA), which are based on the exchange-correlation energy optimization. The fully relaxed structure parameters of Mg2X compounds are in good agreement with the available experimental data. Our results demonstrate that the Mg2X compounds undergo two pressure-induced phase transitions. The first one is from the cubic antifluorite (Fm3¯m) structure to the orthorhombic anticotunnite (Pnma) structure in the pressure range of 3.77–8.78 GPa (GGA) and 4.88–8.16 GPa (LDA). The second transition is from the orthorhombic anticotunnite structure to the hexagonal Ni2In-type (P63m¯mc) structure in the pressure range of 10.41–29.77 GPa (GGA) and 8.89–63.45 GPa (LDA). All the structural parameters of the high pressure phases are analyzed in detail. Only a small difference in the structural parameters is observed at high pressures between the calculated and experimental results. The electronic and thermodynamic properties are also analyzed and discussed. The establishment of the metallic state of the Mg2X (X = Ge, Si and Sn) compounds at high pressure is confirmed

Insights into the optical and electrochemical features of CuAl2O4 nanoparticles and it use for methyl violet oxidation under sunlight exposure

International audienceHerein, the synthesis, optical, and electrochemical characteristics of the spinel CuAl2O4 synthesized by co-precipitation are the focus of this research. As per to the X-ray diffraction (XRD), the obtained sample crystallizes in a cubic symmetry (SG: fd-3m) with a lattice constant of 8.0790 Å. The TEM image revealed spherical nanoparticles with an average build of ∼9 nm and d-spacing of 0.248 nm of the reticular the planes (3 1 1), suggesting the formation of the CuAl2O4 crystalline structure. The optical and dielectric constants, including the extinction coefficient (k), refractive index n (λ), optical conductivity (σopt), dissipation factor (tan δ) and relaxation time (τ) were determined based on diffuse reflectance. The (C−2 - E) graph, plotted in Na2SO4 showed that CuAl2O4, is feature of n-type conduct with a flat band potential of 0.42 VRHE. The EIS spectroscopy displays a semicircle feature with the presence of a constant phase element (CPE) and a bulk resistance of 558 Ω cm2 that lowers to 462.7 Ω cm2 under visible irradiation. As application, the catalytic performance of CuAl2O4 was examined in the breakdown of Methyl violet dye (MV) under sunlight. Within 3 h, an abatement of 89% was obtained, and the oxidation of MV (10 mg/L) follows a first-order kinetic model with a half-life of 82 min. The catalyst can be reused without loss of activity for the first four cycles where •OH and •O2− are accountable of the MV oxidation. © 2022 Elsevier B.V

Predictive markers in elderly patients with estrogen receptor-positive breast cancer treated with aromatase inhibitors: an array-based pharmacogenetic study

So far, no reliable predictive clinicopathological markers of response to aromatase inhibitors (AIs) have been identified, and little is known regarding the role played by host genetics. To identify constitutive predictive markers, an array-based association study was performed in a cohort of 55 elderly hormone-dependent breast cancer (BC) patients treated with third-generation AIs. The array used in this study interrogates variants in 225 drug metabolism and disposition genes with documented functional significance. Six variants emerged as associated with response to AIs: three located in ABCG1, UGT2A1, SLCO3A1 with a good response, two in SLCO3A1 and one in ABCC4 with a poor response. Variants in the AI target CYP19A1 resulted associated with a favourable response only as haplotype; haplotypes with increased response association were also detected for ABCG1 and SLCO3A1. These results highlight the relevance of host genetics in the response to AIs and represent a first step toward precision medicine for elderly BC patients