589 research outputs found

    Marcatili's Lossless Tapers and Bends: an Apparent Paradox and its Solution

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    Numerical results based on an extended BPM algorithm indicate that, in Marcatili's lossless tapers and bends, through-flowing waves are drastically different from standing waves. The source of this surprising behavior is inherent in Maxwell's equations. Indeed, if the magnetic field is correctly derived from the electric one, and the Poynting vector is calculated, then the analytical results are reconciled with the numerical ones. Similar considerations are shown to apply to Gaussian beams in free space.Comment: 4 pages, figures include

    Self-Propagating High-Temperature Synthesis Reactions for ISRU and ISFR Applications

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    In the framework of ISRU (In-Situ Resource Utilization) and ISFR (In-Situ Fabrication and Repair) applications, a novel recently patented process based on the occurrence of Self-propagating High temperature Synthesis (SHS) reactions potentially exploitable for the in-situ fabrication of construction materials in Lunar and Martian environments is described in this work. Specifically, the SHS process involves thermite reactions type between Lunar or Martian regolith simulants and aluminum as reducing agent. To overcome the fact that the original content of ilmenite (FeTiO3) and ferric oxide (Fe2O3) on Moon and Mars soils, respectively, is not enough to make the SHS process possible, suitable amounts of these species have to be added to the starting mixtures. The dependence of the most important processing parameters, particularly the composition of the starting mixture, evacuation level, and gravity conditions, on SHS process behaviour and product characteristics is specifically examined for the case of Lunar regolith. All the obtained findings allows us to conclude that the optimized results obtained under terrestrial conditions are valid for in-situ applications in Lunar environment. In particular, parabolic flight experiments evidenced that neither SHS process dynamics nor product characteristics are significantly influenced in both Lunar and Martian systems when passing from Earth to low gravity conditions. Finally, the complete scheme involving all stages required for the fabrication of physical assets to be used as protection against solar rays, solar wind and meteoroids, etc., is reported.</p

    Remarks on ISRU and ISFR Technologies for Manned Missions on Moon and Mars

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    Space colonization and exploitation of extra-terrestrial natural resources could help humanity in facing various Earth problems. In this regard, production of energy and materials starting from Moon and Mars natural resources as well as the transportation of humans in space could be considered the long term remedy to issues such as overpopulation, depletion of fossil fuels, climate change as well as reduction of available natural resources. Along theses lines, two recently filed patents related to use of novel technologies for the in situ exploitation of natural resources available on Moon and Mars have been developed

    ACTN-3 and ACE genotypes in elite male Italian athletes

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    The ACE I/D and the ACTN-3 R577X polymorphisms are the most studied genes associated with elite athlete status, even if this association has been often conflicting. The aim of the present study was to investigate the association between the ACE and the ACTN3 genotypes and elite performance in Italian male athletes. The ACTN-3 R577X and the ACE I/D genotype distributions of 59 elite male Italian athletes practicing gymnastics (G; n = 17), 100 m-400 m running (R; n = 12), and playing soccer (S; n= 30) were compared with controls from Italian (C; n = 31) populations. For ACE distribution, athletes did not differ from controls (G, X2 = 0.37, df = 2, p = 0.82; R, X2 = 1.90, df = 2, p = 0.45; S, X2 = 1.48, df = 2, p = 0.47) and the DD genotype was at very high frequency in all groups (G = 53%, R= 50%, S = 60%, C = 45%). For ACTN-3 distribution, elite gymnasts showed a significant difference from controls (X2 = 6.57, df = 2, p = 0.03), showing an absence of XX genotype. Soccer players and runners did not differ from controls in ACTN-3 genotype distribution (R, X2 =0.43, df = 2, p = 0.80; S, X 2 = 1.25, df = 2, p = 0.53). Even if the ACE DD genotype is often positively associated with elite sprint/power athlete status, its high frequency in Italian populations eliminates the possibility of its exclusive association in Italian athletes. The results of ACTN3 genotypes suggest that RR genotype of ACTN-3 gene is a determinant of elite gymnasts status but it is not the key factor for achieving a top-level performance in soccer or track events

    Heart applications of 4D flow

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    Four-dimensional (4D) flow sequences are an innovative type of MR sequences based upon phase contrast (PC) sequences which are a type of application of Angio-MRI together with the Time of Flight (TOF) sequences and Contrast-Enhanced Magnetic Resonance Acquisition (CE-MRA). They share the basic principles of PC, but unlike PC sequences, 4D flow has velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage. They guarantee the analysis of flow with multiplanarity on a post-processing level, which is a unique feature among MR sequences. Furthermore, this technique provides a completely new level to the in vivo flow analysis as it allows measurements in never studied districts such as intracranial applications or some parts of the heart never studied with echo-color-doppler, which is its sonographic equivalent. Furthermore, this technique provides a completely new level to the in vivo flow analysis as it allows accurate measurement of the flows in different districts (e.g., intracranial, cardiac) that are usually studied with echo-color-doppler, which is its sonographic equivalent. Of note, the technique has proved to be affected by less inter and intra-observer variability in several application. 4D-flow basic principles, advantages, limitations, common pitfalls and artefacts are described. This review will outline the basis of the formation of PC image, the construction of a 4D-flow and the huge impact the technique is having on the cardiovascular non-invasive examination. It will be then studied how this technique has had a huge impact on cardiovascular examinations especially on a central heart level

    Physical Assets by SHS in the Framework of ISRU and ISFR Paradigms for Human Space Missions on the Moon

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    In this work a brief overview of the most important technologies for space exploration, with particular emphasis on the Moon missions, is presented. It is shown that the focus has been on the technologies to extract consumables (O2, H2O, N2) for human life-support replenishment. The fact that the exploitation of extraterrestrial resources to obtain the desired materials during each ongoing mission, which has been the subject of several investigations since the sixties of the last century, is discussed. The paradigms ISRU (In Situ Resources Utilization) and ISFR (In Situ Fabrication and Repair) are then introduced. In particular, one of the most important process for the production of oxygen, i.e. the reduction of ilmenite by hydrogen is analyzed. In addition, the current iteration of the roadmap which identifies two feasible pathways for human missions after ISS (International Space Station) is addressed. Next, the fabrication of Lunar physical assets is taken into account, while focusing particularly on those processes where combustion-like reactions are exploited. The main results recently obtained in the literature in this regards are also summarized. In particular, the choice of the reducing agent and the influence of the most important processing parameters (composition of the starting mixture, gas pressure level, and gravity conditions) are examined in a systematic manner

    Effects of industrial processing on pesticide multiresidues transfer from raw tomatoes to processed products

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    Pesticides are broadly used to improve food safety, although they can lead to adverse health effects on consumers. Various food processing approaches, at the industrial or domestic level, have been found to highly reduce the amount of pesticide residues in most food materials. In this work, samples of raw tomatoes were collected directly from the field and processed at the industrial level to produce purée, triple concentrated paste, fine pulp, and diced tomatoes. A multiresidue method based on a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged e Safe) sample preparation, followed by liquid chromatography‐tandem mass spectrometry analysis (LC‐MS/MS) for the assessment of 116 pesticides residues, was used. The analytical method has been validated according to SANTE indications. The recovery yields ranged from 75.5% to 115.3%, repeatability (RSDr) ranged from 3.4% to 18.3%, while reproducibility (RSDwR) ranged from 5.4% to 19.8%. The limit of quantifications (LOQs) ranged from 2.35 μg kg−1 for benthiavalicarb to 6.49 μg kg−1 for allethrin. A total of 159 raw tomato samples were collected from the field. The analysis showed the presence of 46 pesticides with azoxystrobin and chlorantraniliprole the most represented. On the other hand, all industrially processed samples showed values ≤ LOD, confirming that post‐harvest processes can lead to a decrease in pesticide residues from agricultural commodities

    Influence of the technological process on the biochemical composition of fresh roe and bottarga from liza ramada and mugil cephalus

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    Bottarga is a high-priced delicacy with high nutritional value, and, in Italy, bottarga from mullets has been recognized to be a traditional food product. The flathead grey mullet Mugil cephalus and the thinlip grey mullet Liza ramada are the main cultured grey mullets in the Mediterranean Sea. In this study, fresh roe and bottarga from these two species were investigated to evaluate the influence of the technological process and the species on their biochemical composition and health advantages. The 1 h/200 g salting-out step did not increase the levels of NaCl in the bottarga, although it highly decreased the levels of some heavy metals like Cu and Al. Processing of fresh roe in bottarga led to an essential modification of the lipid fraction, following a general series of monousatturated fatty acid (MUFA)&gt; poliunsutturated fatti acid (PUFA) &gt; saturated fatty acid (SAFA) and an increase in both !3 and !6 in Liza ramada. Moreover, bottarga showed higher levels of squalene and cholesterol and an increased Essential Amino Acid/Total Amino Acid ratio (EAA/TAA) in both species. In addition to the nutritional benefits for the consumer, the process proposed in this study may represent a reliable tool for local producers to obtain a final bottarga with both a reproducible biochemical composition and organoleptic characteristics
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