Nonequilibrium stationary states of 3D self-gravitating systems

Three dimensional self-gravitating systems do not evolve to thermodynamic equilibrium, but become trapped in nonequilibrium quasistationary states. In this Letter we present a theory which allows us to a priori predict the particle distribution in a final quasistationary state to which a self-gravitating system will evolve from an initial condition which is isotropic in particle velocities and satisfies a virial constraint 2K=-U, where K is the total kinetic energy and U is the potential energy of the system

A Comparative Study

This research was funded by EU funds through the FEDER European Regional Development Fund (project LISBOA-02-0145-FEDER-031311) project LA/P/0056/2020 of Institute of Molecular Sciences, and LA/P/0140/2020 of i4HB, project UID/EEA/00066/2020 from the Center of Technology and Systems, and from the Instituto Politécnico de Lisboa with IPL/2018/STREAM_ISEL and IPL/2020/AGE-SPReS_ISEL projects. APCR and AMF thank the Instituto Superior Técnico for the scientific employment contracts IST-ID/119/2018 and IST-ID/131/2018, respectively. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Aiming to develop a nanoparticle-based optical biosensor using gold nanoparticles (AuNPs) synthesized using green methods and supported by carbon-based nanomaterials, we studied the role of carbon derivatives in promoting AuNPs localized surface plasmon resonance (LSPR), as well as their morphology, dispersion, and stability. Carbon derivatives are expected to work as immobi-lization platforms for AuNPs, improving their analytical performance. Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4·3H2O using phytochemicals (from tea) which act as both reducing and capping agents. UV–Vis spectroscopy, transmission electron microscopy (TEM), zeta potential (ζ-potential), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNPs and nanocomposites. The addition of reduced graphene oxide (rGO) resulted in greater dispersion of AuNPs on the rGO surface compared with carbon-based nanomaterials used as a support. Differences in morphology due to the nature of the carbon support were observed and are discussed here. AuNPs/rGO seem to be the most promising candidates for the development of LSPR biosensors among the three composites we studied (AuNPs/G, AuNPs/GO, and AuNPs/rGO). Simulations based on the Mie scattering theory have been used to outline the effect of the phytochemicals on LSPR, showing that when the presence of the residuals is limited to the formation of a thin capping layer, the quality of the plasmonic resonance is not affected. A further discussion of the application framework is presented.publishersversionpublishe

Low velocity impact study of vacuum bag infused bouligand inspired composites

This work proposes three Bouligand-inspired layups to enhance low velocity impact (LVI) damage resistance and tolerance of convectional aircraft composite laminates. Two Bouligand-like (HL and HL_S) and one hybrid design layup, merging conventional and Bouligand architecture (HYB), were produced by vacuum bag infusion. Their performance under LVI, at 13.5, 25 and40 (J), and compression after impact (CAI) tests were evaluated and comparedwith a conventional aircraft multidirectional layup (LS) produced under identical conditions. Results demonstrated that, especially for the higher impact energy levels, both Bouligand-like laminates consistently outperformed all the other configurations, exhibiting higher load bearing capacity (peak load) and energy absorption. Additionally, the rough and poorly defined interlaminar region of Bouligand-like layups have showed to delay severe damage for higher loads and energies, dissipating all (at 13.5 J) or most of the impact energy (more than 50%) through subcritical damage mechanisms. Compared with LS laminate, Bouligand-inspired layups postponed the onset of severe damage thresholds by up to 120% in load and 66% in energy (HL laminate) while developing smaller and more localized damages. The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance

Bioinspired architectures toward improving damage resistance on CFRP laminates

Carbon fibre reinforced polymers (CFRP) are widely used in advanced applications due to their high performance and low weight, however, under certain conditions, they tend to develop internal damages that may compromise the component performance in service. Low velocity impact (LVI) events are one of the most common and dangerous solicitations that CFRP laminates must face during their life time, under these conditions they tend to develop so-called barely visible impact damages (BVID) that may propagate in service. To improve damage tolerance to LVI events, three new bioinspired CFRP laminates were developed and their mechanical properties and impact behaviour were compared to a typical aeronautic standard laminate in this work. All these studied laminates, having approximately the same thickness of 4 mm, were produced by vacuum bag infusion and observed under scanning electron microscopes (SEM) for assessing their processing quality. Tensile, interlaminar shear strength (ILSS) and LVI tests were performed in order to evaluate their Young’s modules, global delamination resistance and impact response. LVI tests were performed for all laminates at the four different impact energy levels of 13.5, 25, 40 and 80 J and damage shape and areas were subsequentially evaluated by ultrasonic C-scan. SEM observations and the good agreement between theoretical and experimental Young’s modules results demonstrated a processing quality. ILSS results have shown that the bioinspired hybrid laminate (HYB) presented better global resistance to delamination when compared to the other laminates. LVI tests and C-scan inspection have also demonstrated that HL and HL_S laminates exhibited higher resistance to damage propagation and smaller damaged area, respectively.FCT, Programa MIT Portugal, projeto “IAMAT – Introduction of advanced materials technologies into new product development for the mobility industries

Thin veils strategically interleaved to reduce low velocity damages on CFRP

Low velocity impact (LVI) events on carbon fibre reinforced polymers (CFRP) are one of the most problematic issues in composite applications for advanced markets, such as aeronautic, aerospace and army. Due to their own brittleness and layer-by-layer nature, when exposed to LVI solicitations, composites tend to develop internal damages that may be barely visible at naked eye. The high complex field of internal stresses developed in composite laminates during impact usually causes crack initiation and defects between layers, which may propagate (delamination) due to the low toughness that this unreinforced resin rich region exhibits. In this work, to try minimizing this propagation problem, thin veils of different materials (glass, carbon, aramid and polyester), were interleaved between different layers of a carbon/epoxy laminate typically used to produce aircraft components. In addition, to decide between which layers could be better interleave the above referred veils a theoretical study was carried out to evaluate the stresses distribution across laminate thickness when a bending moment is applied, on a carbon/epoxy laminate under study. The new carbon/epoxy laminates using the thin interleaved veils were produced by vacuum bag infusion and their mechanical characteristics and LVI responses compared with those obtained on a non-interleaved one produced in the same processing conditions. Interlaminar shear strength (ILSS) and LVI tests at four different energy impact levels were performed in order to evaluate the respective characteristics of the laminates, their damage tolerance and impact response. All laminates studied were also observed under scanning electron microscopes (SEM) for assessing their processing quality.FCT, Programa MIT Portugal, projeto “IAMAT – Introduction of advanced materials technologies into new product development for the mobility industries

Effects of Resistance Exercise on Endothelial Progenitor Cell Mobilization in Women

This study aimed to determine the effect of a single bout of resistance exercise at different intensities on the mobilization of circulating EPCs over 24 hours in women. In addition, the angiogenic factors stromal cell-derived factor 1 (SDF-1α), vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1-alpha (HIF-1α) and erythropoietin (EPO) were measured as potential mechanisms for exercise-induced EPCs mobilization. Thirty-eight women performed a resistance exercise session at an intensity of 60% (n = 13), 70% (n = 12) or 80% (n = 13) of one repetition maximum. Each session was comprised of three sets of 12 repetitions of four exercises: bench press, dumbbell curl, dumbbell squat, and standing dumbbell upright row. Blood was sampled at baseline and immediately, 6 hours, and 24 hours post-exercise. Circulating EPC and levels of VEGF, HIF-1α and EPO were significantly higher after exercise (P \u3c 0.05). The change in EPCs from baseline was greatest in the 80% group (P \u3c 0.05), reaching the highest at 6 hours post-exercise. The change in EPCs from baseline to 6 hours post-exercise was correlated with the change in VEGF (r = 0.492, P = 0.002) and HIF-1α (r = 0.388, P = 0.016). In general, a dose-response relationship was observed, with the highest exercise intensities promoting the highest increases in EPCs and angiogenic factors

Carbon nanotubes based multi-directional strain sensor

In this work a new carbon nanotubes (CNT) based multi-directional strain sensor capable of quantifying and indicate strain direction is foreseen. This work investigates the electromechanical behavior of an aligned CNT sensing patch strained at 45◦ in order to validate its multi-directional sensing capability. Vertically aligned CNT forests are produced by chemical vapor deposition (CVD) and then mechanically knocked down onto polyimide (PI) films. Two configurations, diamond (D sample) and square (Sq sample), are considered. The relative electrical resistance (ΔR/R0) and the electrical anisotropy (RB/RA) upon strain increments are analyzed and compared to previous work results (0◦ and 90◦ strain direction). Both 45◦ samples, D and Sq, are sensitive to strain. A correlation between electrical anisotropy behavior and strain direction (0◦, 45◦ and 90◦) is established. The results show that with only an aligned CNT small patch it is possible to quantify and indicate strain in three directions.This work was partially funded under the project “IAMAT – Introduction of advanced materials technologies into new product development for the mobility industries”, with reference MITP-TB/PFM/0005/2013, under the MIT-Portugal program exclusively financed by FCT – Fundação para a Ciência e Tecnologia. This work was also co-financed by national funds through FCT – Fundação para a Ciência e Tecnologia, with the scope of projects with references UIDB/05256/2020 and UIDP/05256/2020”

Commercial Gold Complexes Supported on Functionalised Carbon Materials as Efficient Catalysts for the Direct Oxidation of Ethane to Acetic Acid

UIDB/00100/2020 UIDP/00100/2020 LA/P/0056/2020 IST-ID/119/2018 SFRH/BD/146426/2019 CEEC-INST/00102/2018 UIDB/50006/2020 UIDP/50006/2020 Base-UIDB/50020/2020 Programmatic-UIDP/50020/2020The single-pot efficient oxidation of ethane to acetic acid catalysed by Au(I) or Au(III) compounds, chlorotriphenylphosphinegold(I) (1), chlorotrimethylphosphinegold(I) (2), 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidenegold(I) chloride (3), dichloro(2-pyridinecarboxylato)gold(III) (4), homogenous and supported on different carbon materials: activated carbon (AC), multi-walled carbon nanotubes (CNT) and carbon xerogel (CX), oxidised with nitric acid followed by treatment with NaOH (-ox-Na), is reported. The reactions were performed in water/acetonitrile. The materials were selective for the production of acetic acid, with no trace of by-products being detected. The best homogenous catalysts were complexes 2 and 3 which showed the highest ethane conversion and an acetic acid yield of ca. 21%, followed by 4 and 1. The heterogenised materials showed much better activity than the homogenous counterparts, with acetic acid yields up to 41.4% for 4@CNT-ox-Na, and remarkable selectivity (with acetic acid being the only product detected). The heterogenised catalysts with the best results were reused up to five cycles, with no significant loss of activity, and maintaining high selectivity for acetic acid. 4@CNT-ox-Na showed not only the best catalytic activity but also the best stability during the recycling runs.publishersversionpublishe

Binary Mutual Diffusion Coefficients of Isoniazid Aqueous Solutions at (298.15 and 310.15) K

Binary mutual diffusion coefficients measured by the Taylor dispersion method in two different laboratories (University of Naples, Federico II, Italy, and University of Coimbra, Portugal) are reported for aqueous solutions of isoniazid at concentrations from (0.000 to 0.100) mol·dm−3 and at two temperatures (298.15 and 310.15) K. The hydrodynamic radii for the isoniazid in aqueous solution are calculated from the experimental results. In addition, the Hartley equation and the experimental diffusion coefficients are used to estimate activity coefficients for aqueous isoniazid at both temperature