489 research outputs found
New Stationary Frame Control Scheme for Three Phase PWM Rectifiers Under Unbalanced Voltage Dips Conditions
No full textA new stationary frame control scheme for three-phase pulsewidth-modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage ripple. This paper's novelty is the development of a new current-reference generator implemented directly in stationary reference frame. This allows using proportional sinusoidal signal integrator (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components. No phase-locked loop (PLL) strategies and coordinate transformations are needed for the proposed current-reference generator. Experimental results are presented for a 20-kV A alternative current (ac)/direct current (dc) converter prototype to demonstrate the effectiveness of the proposed control scheme. A comparison with two other existing control techniques is also performed. Fast dynamic performance with small dc-link voltage ripple and input sinusoidal currents are obtained with this control scheme, even under severe voltage dips operating condition
Impact of the New Measurement of the 12C + 12C Fusion Cross Section on the Final Compactness of Massive Stars
No full textWe discuss how the new measurement of the 12C + 12C fusion cross section carried out with the Trojan Horse Method affects the compactness of a star, i.e., basically the binding energy of the inner mantle, at the onset of the core collapse. In particular, we find that this new cross section significantly changes the dependence of the compactness on the initial mass with respect to previous findings obtained in Chieffi & Limongi by adopting the classical cross section provided by Caughlan & Fowler. A non-monotonic but well-defined behavior is also confirmed in this case and no scatter of the compactness around the main trend is found. Such an occurrence could impact the possible explodability of the stars
New Stationary Frame Control Scheme for Three Phase PWM Rectifiers under Unbalanced Voltage Dips Conditions
No full text
Environmental factors determining growth of salamander larvae : a field study
No full textLarval growth and survival of organisms are strongly influenced by abiotic and biotic factors, as demonstrated by experimental studies performed under controlled laboratory or semi-natural conditions. Even if they have many advantages, experiments cannot cover the full complexity of natural conditions and field studies are needed for a better understanding of how environmental variation determines growth and development rate. Fire salamander Salamandra salamandra females give birth to larvae in a variety of habitats, both epigean and subterranean. In caves, salamander larvae successfully grow and metamorphose, but their growth is more than three times longer than in epigean streams and factors determining these differences require investigation. We performed a field study to understand the factors related to the growth of fire salamander larvae in different environmental conditions, evaluating the relationship between environmental features and larval growth and differences between caves and epigean spring habitats. Both caves and epigean larvae successfully grew. Capture-mark-recapture allowed to individually track individuals along their whole development, and measure their performance. Growth rate was significantly affected by environmental variables: larvae grew faster in environments with abundant invertebrates and few conspecifics. Taking into account the effect of environmental variables, larval growth was significantly lower in caves. Food availability plays a different effect in the two environments. Larval growth was positively related to the availability of invertebrates in epigean sites only. The development rate of hypogeous populations of salamanders is slower because of multiple parameters, but biotic factors play a much stronger role than the abiotic ones
X-ray emission from plasma produced by a Nd:YAG/glass laser on a Cu target: A preliminary analysis
No full textIn this article, we present a preliminary study of the soft X-ray emission by a Cu plasma, obtained by focalizing a Nd:YAG/glass laser beam on a copper target at λ =532nm (second harmonic) at a laser intensity I ≈ 10 12W/cm2. The pulse duration is tL=6ns and the laser shot energy EL ranges from 200 to 300mJ. We have measured the average X-ray spectral emission and determined the X-ray conversion efficiency, (% 2 π sr) in the aluminum transmission window at 70eV with a harder X-ray tail at about 700eV. A study of angular distribution of X-ray intensity emitted from the plasma is presented too
Peer review report for: Chocolates and 'Legrias': Dilemma of the best sales channel
No full textPEER REVIEW REPORT FOR:
Silva, A. L. B., Limongi, R., Gomes, A. C., & Pimenta, D. (2021). Chocolates and ‘Legrias’: Dilemma of the best sales channel. Revista de Administração Contemporânea, 25(spe), e200235. https://doi.org/10.1590/1982-7849rac2021200235.en
HOW TO CITE THIS PEER REVIEW REPORT:
Silva, A. L. B., Limongi, R., Gomes, A. C., Pimenta, D., Passos, A. P., & Freitas, F. D. (2021). Peer review report for: Chocolates and ‘Legrias’: Dilemma of the best sales channel. RAC. Revista de Administração Contemporânea. Zenodo.
https://doi.org/10.5281/zenodo.4537486
REVIEWERS:
Ana Paula Passos (Universidade do Vale do Itajaí, Brazil)
Flavia D'Albergaria Freitas (Universidade Federal do Rio de Janeiro, COPPEAD, Brazil
The shielding effect of phospholipidic bilayers on zinc oxide nanocrystals for biomedical applications
No full textZinc oxide nanocrystals (ZnO NCs), thanks to their unique properties, are receiving much attention for their use in nanomedicine, in particular for therapy against cancer [1]. To be efficiently employed as diagnostic and therapeutic (yet theranostic) tools [2], highly dispersed, stable and non-toxic nanoparticles are required. In the case of ZnO NCs, there is still a lack of knowledge about cytotoxicity mechanisms and stability in the biological context, as well as immunological response and haemocompatible features. Most of these above-mentioned behaviours strongly depends on physico-chemical and surface properties of the nanoparticles. We thus propose a novel approach to stabilize the ZnO NCs in various biological media, focusing on NC aggregation and biodegradation as a function of the surface functionalization. We synthesized bare ZnO NCs, amino-propyl functionalized ones, and lipid bilayer-shielded NCs, and we characterized their morphological, chemical and physical properties. The stability behavior of the three different samples was evaluated, comparing their biodegradation profiles in different media, i.e. organic solvents, water, and different simulated and biological fluids. The studies aim to investigate how the particle surface functionalizations, and thus chemistry and charge, could influence their hydrodynamic size, zeta potential and consequent aggregation and degradation in the different solvents. We demonstrated that bare and amino-functionalized ZnO NCs strongly and rapidly aggregate when suspended in both simulated and biological media. Long-term biodegradation analysis showed small dissolution into potentially cytotoxic Zn-cations, also slightly affecting their crystalline structure. In contrast, high colloidal stability and integrity was retained for lipid-shielded ZnO NCs in all media, rendering them the ideal candidates for further theranostic applications [3]. [1] P. Zhu, Z. Weng, X. Li, X. Liu, S. Wu Adv. Mater. Interfaces 3 (2016) 1500494. [2] E. Lim, T. Kim, S. Paik, S. Haam, Y. Huh, and K. Lee, Chem. Rev. 115 (2015) 327−394. [3] B. Dumontel, M. Canta, H. Engelke, A. Chiodoni, L. Racca, A. Ancona, T. Limongi, G. Canavese and V. Cauda, J. Mater. Chem. B, under review The support from ERC Starting Grant - Project N. 678151 "Trojananohorse" and Compagnia di Sanpaolo are gratefully acknowledged
Turriglomina ZANINETTI, n. gen., un nouveau nom pour "TurriteIIeIIa" mesotriassica KOEHN-ZANINETTI, 1968 (Foraminifère, Trias moyen): avec remarque sur la présence de l'espèce dans le Ladinien de I'Apennin méridional
No full textStudy of the relationships between fragile sites, chromosome breaks and sister chromatid exchanges.
No full textThis paper reports the results of an investigation into the relationship between common fragile sites and sister chromatid exchanges (SCE). Human leukocyte cultures were grown in two different media, one complete (RPMI 1640) and one deficient in folic acid and thymidine (199M). Some of the cultures were treated with DAPI, a non-intercalating compound which binds preferentially to the AT bases of DNA and is capable of inducing fragile sites. Bromodeoxyuridine (BrdU) was added to all the cultures for SCE analysis. Chromomycin A3 was used for mapping lesions and SCEs by R-banding. A total of 400 cells was examined. The main results show that: BrdU, probably by re-equilibrating the unbalanced nucleotide pool of the 199 culture medium, interferes with the synergism between this culture medium and DAPI in inducing the expression of fragile sites; the SCE frequency per cell is not increased by DAPI in both culture media, therefore this compound does not seem to cause any damage to the DNA and seems merely to act by inhibiting the normal condensation of a subset of fragile sites that possess DAPI-specific base sequences; even in the absence of chromosomal lesions, the fragile sites are significantly preferred as SCE sites to non-fragile sites, whereas in the presence of a lesion, both fragile and non-fragile sites have the same likelihood of undergoing SCE. All this indicates that the presence of a lesion strongly favours SCE formation and that common fragile sites are probably chromosome regions preferentially damaged during the S phase
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