IR-based satellite and radar rainfall estimates of convective storms over northern Italy

Convective precipitation events in northern Italy during 1996 and 1997 are analysed using two infrared-based geosynchronous satellite rainfall estimation methods to verify the level of applicability of the techniques for operational applications in the area, their quantitative results, and relative performances. The Negri–Adler–Wetzel (NAW) and the convective stratiform technique (CST) are applied to METEOSAT's thermal infrared (IR) data. C-band radar reflectivity fields detail the vertical and horizontal structure of the cloud systems, and radar rainfall data are retrieved. Satellite rain areas are checked against simultaneous radar rainfall retrievals through a contingency analysis procedure. A semi-quantitative analysis is presented. Positive brightness temperature differences between water vapour and thermal IR channels are also examined and related to the storms' development stage and rainrate. Results show that NAW and CST perform reasonably in delimiting rain areas during active convection and care should be used in the initial and final development stage when statistical parameters lose most of their significance. NAW tends to overestimate rainfall while CST approaches more closely radar measurements. Most common errors arise from considering only portions of the storm, contamination from cold non-precipitating cloud, and merging of two or more cloud masses of independent origin. Operational applications, though not completely quantitative, are also possible, including positive values of the difference between water vapour and IR brightness temperature

Recent Applications of Melanin-like Nanoparticles as Antioxidant Agents

Nanosized antioxidants are highly advantageous in terms of versatility and pharmacokinetics, with respect to conventional molecular ones. Melanin-like materials, artificial species inspired by natural melanin, combine recognized antioxidant (AOX) activity with a unique versatility of preparation and modification. Due to this versatility and documented biocompatibility, artificial melanin has been incorporated into a variety of nanoparticles (NP) in order to give new platforms for nanomedicine with enhanced AOX activity. In this review article, we first discuss the chemical mechanisms behind the AOX activity of materials in the context of the inhibition of the radical chain reaction responsible for the peroxidation of biomolecules. We also focus briefly on the AOX properties of melanin-like NP, considering the effect of parameters such as size, preparation methods and surface functionalization on them. Then, we consider the most recent and relevant applications of AOX melanin-like NPs that are able to counteract ferroptosis and be involved in the treatment of important diseases that affect, e.g., the cardiovascular and nervous systems, as well as the kidneys, liver and articulations. A specific section will be dedicated to cancer treatment, since the role of melanin in this context is still very debated. Finally, we propose future strategies in AOX development for a better chemical understanding of melanin-like materials. In particular, the composition and structure of these materials are still debated, and they present a high level of variability. Thus, a better understanding of the mechanism behind the interaction of melanin-like nanostructures with different radicals and highly reactive species would be highly advantageous for the design of more effective and specific AOX nano-agents

Effects of propagation conditions on radar beam-ground interaction: impact on data quality

International audienceA large part of the research in the radar meteorology is devoted to the evaluation of the radar data quality and to the radar data processing. Even when, a set of absolute quality indexes can be produced (like as ground clutter presence, beam blockage rate, distance from radar, etc.), the final product quality has to be determined as a function of the task and of all the processing steps. In this paper the emphasis lies on the estimate of the rainfall at the ground level taking extra care for the correction for ground clutter and beam blockage, that are two main problems affecting radar reflectivity data in complex orography. In this work a combined algorithm is presented that avoids and/or corrects for these two effects. To achieve this existing methods are modified and integrated with the analysis of radar signal propagation in different atmospheric conditions. The atmospheric refractivity profile is retrieved from the nearest in space and time radiosounding. This measured profile is then used to define the `dynamic map' used as a declutter base-field. Then beam blockage correction is applied to the data at the scan elevations computed from this map. Two case studies are used to illustrate the proposed algorithm. One is a summer event with anomalous propagation conditions and the other one is a winter event. The new algorithm is compared to a previous method of clutter removal based only on static maps of clear air and vertical reflectivity continuity test. The improvement in rain estimate is evaluated applying statistical analysis and using rain gauges data. The better scores are related mostly to the ``optimum" choice of the elevation maps, introduced by the more accurate description of the signal propagation. Finally, a data quality indicator is introduced as an output of this scheme. This indicator has been obtained from the general scheme, which takes into account all radar data processing steps

A synergic nanoantioxidant based on covalently modified halloysite-trolox nanotubes with intra-lumen loaded quercetin

We describe the preparation and properties of the first example of a synergic nanoantioxidant, obtained by different functionalizations of the external surface and the inner lumen of halloysite nanotubes (HNTs). Trolox, a mimic of natural α-tocopherol, was selectively grafted on the HNT external surface; while quercetin, a natural polyphenolic antioxidant, was loaded into the inner lumen to afford a bi-functional nanoantioxidant, HNT-Trolox/Que, which was investigated for its reactivity with transient peroxyl radicals and a persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical in comparison with the corresponding mono-functional analogues HNT-Trolox and HNT/Que. Both HNT-Trolox and HNT/Que showed good antioxidant performance in the inhibited autoxidation of organic substrates; however HNT-Trolox/Que protection by reaction with peroxyl radicals was 35% higher in acetonitrile and 65% in chlorobenzene, as compared to the expected performance based on the sum of contributions of NHT-Trolox and NHT/Que. Similar enhancement was observed also in the trapping of DPPH• radicals. Synergism between the distinct antioxidant functions was based on the rapid reaction of externally exposed Trolox (rate constant with peroxyl radicals was 1.1 × 106 M-1 s-1 and 9 × 104 M-1 s-1 respectively in chlorobenzene and acetonitrile, at 30 °C), followed by its regeneration by quercetin released from the HNT lumen. The advantages of this novel nanoantioxidant are discussed

From the dual function lead AP2238 to AP2469, a multi-target-directed ligand for the treatment of Alzheimer\u2019s disease

The development of drugs with different pharmacological properties appears to be an innovative therapeutic approach for Alzheimer\u2019s disease. In this article, we describe a simple structural modification of AP2238, a first dual function lead, in particular the introduction of the catechol moiety performed in order to search for multi-target ligands. The new compound AP2469 retains antiacetylcholinesterase (AChE) and beta-site amyloid precursor protein cleaving enzyme (BACE)1 activities compared to the reference, and is also able to inhibit Ab42 self aggregation, Ab42 oligomer-binding to cell membrane and subsequently reactive oxygen species formation in both neuronal and microglial cells. The ability of AP2469 to interfere with Ab42 oligomer-binding to neuron and microglial cell membrane gives this molecule both neuroprotective and antiinflammatory properties. These findings, together with its strong chain-breaking antioxidant performance, make AP2469 a potential drug able to modify the course of the diseas