1,721,267 research outputs found
Regional assessment of daily reference evapotranspiration: Can ground observations be replaced by blending ERA5-Land meteorological reanalysis and CM-SAF satellite-based radiation data?
Full text linkThis study evaluates the accuracy of daily reference evapotranspiration (ETo), computed according to the FAO Penman-Monteith equation by using a set of input weather variables obtained by blending ERA5-Land (ERA5L) reanalysis data with surface incoming solar radiation (Rs) provided by the instruments on board the Meteosat geostationary satellites, operationally delivered by the Satellite Applications Facility on Climate Monitoring (CM-SAF). Performance assessment was carried out in Sicily (southern Italy) by using data from 38 automatic ground weather stations (AWSs) for years 2003–2020. ERA5L and CM-SAF data were first downscaled and bias-corrected with a calibration dataset; ERA5L air temperature data were also downscaled by lapse-rate correction. ETo estimates obtained with the blended ERA5L and CM-SAF validation dataset (ERA5L+CM-SAF) were compared with two other ETo estimates respectively obtained by using ERA5L and interpolated ground weather data (IGD). Performance indicators of the IGD dataset were evaluated by recursively applying universal kriging or ordinary kriging to the observed weather data, according to a cross-validation procedure. Rs provided by CM-SAF outperformed Rs obtained by ground interpolation, thus confirming the convenience of using bias-corrected CM-SAF data even when ground observations are available in the study area. ETo estimates with ERA5L+CM-SAF showed a normalized RMSE of 12%, outperforming ERA5L ETo estimates while performing comparably to ETo estimates obtained with the IGD dataset. The results suggested that the proposed blended dataset is a good proxy for interpolated ground weather observations in the assessment of ETo at regional scale when weather measurements cannot be easily gathered or in data-sparse regions
Two-photon interactions at single fluorescent molecule level
No full textSingle-molecule spectroscopy and single-molecule detec-tion are emerging areas that have many applications when combinedwith scanning, imaging, and spectroscopy techniques. We have com-bined a commercial confocal scanning head, to a Ti:sapphire laserand to an inverted microscope, for the detection of single moleculefluorescence of varies dyes by two-photon excitation. We collectedspot images of fluorescent molecules that have been deposited on asubstrate considering both blinking and photobleaching behavior of fluorescent spots. Here, we report data related to two-photon interac-tions that occur with the following fluorescent molecules: Indo-1,Rhodamine 6G, Fluorescein, and Pyrene. The choice of these specificdyes is based upon their wide use in biological and medical applica-tions together with the varying complexity of their chemical structurethat increases from Pyrene to Indo-1. Moreover, we report some dataabout single molecule studies related to denaturation of an enhancedgreen fluorescent protein, GFPmut2, under one photon excitation re-gime, that show a very similar trend to that observed for the alreadymentioned fluorescent molecules
Photothermally Active Inorganic Nanoparticles: from Colloidal Solutions to Photothermally Active Printed Surfaces and Polymeric Nanocomposite Materials
No full textNanoparticles with absorption in Near-Infrared (NIR)
region and subsequent efficient release of heat, are receiving
great attention due to wide opportunities of applications in
different fields including biotechnology and nanomedicine.
However, the colloidal solutions of such nanoparticles may have
limitations in effective application connected with long-term
stability of nanoparticle solutions and possible re-usability.
Therefore, this minireview focuses on the state-of-the art of research
and application of photothermally active nanoparticles
to engineer remotely activated materials with controllable photothermal
properties: printed surfaces and polymeric nanocomposite
materials. We highlight in this minireview different types
of photothermally active nanoparticles (e.g. non-spherical gold
nanoparticles, copper sulfide nanoparticles) that already have
been applied for fabrication of printed patterns and polymeric
nanocomposites, the properties of the resulting materials and
further application opportunitie
Rainfall Extraordinary Extreme Events (EEEs) Frequency and Magnitude Assessment: The EEE Occurred on 14th–15th October 2015 in Benevento Area (Southern Italy)
No full textThe identification of suitable statistical models of rainfall maxima at regional scale is a key element for the definition of reliable flood and landslide risk mitigation plans and for the design and security evaluation of high hazard strategic engineering structures. The ability to develop such models is highly dependent on a rain gauge monitoring network able to observe the extreme events that occurred in a region for several decades. In Italy, the density of the monitoring network and the time series lengths are often inadequate to capture some of the rainfall extreme events (referred to as extraordinary extreme events - EEEs), characterized by very low frequencies and spatial extent scales much smaller than those of rainfall ordinary maxima. In recent years, new operational statistical approaches were proposed to properly retrieve the EEEs frequency from the available database. However, the meteorological patterns of the EEEs are still poorly known, due to the limited number of documented cases studies available. The post-event rainfall analysis of observed EEEs and the evaluation of the efficiency of the monitoring network in detecting their magnitude and spatial properties may certainly help to improve the interpretation of the phenomena and their probabilistic modeling. In this study, new insights about the characteristics of EEEs are retrieved by analyzing data collected by different automatic rain gauge networks operating in Campania region (Southern Italy) from year 2001 to 2020. In this time frame, the extreme rainfall event occurred on 14th–15th October 2015 in Benevento area is the only daily EEE observed. The analyses show the capability of different monitoring networks to observe the phenomenon and the impact of different statistical regional models of rainfall maxima in assessing its frequency
Two-photon fluorescence excitation and related techniques in biological microscopy
No full textThis review is concerned with two-photon excited fluorescence microscopy (2PE) and related techniques, which are probably the most important advance in optical microscopy of biological specimens since the introduction of confocal imaging. The advent of 2PE on the scene allowed the design and performance of many unimaginable biological studies from the single cell to the tissue level, and even to whole animals, at a resolution ranging from the classical hundreds of nanometres to the single molecule size. Moreover, 2PE enabled long-term imaging of in vivo biological specimens, image generation from deeper tissue depth, and higher signal-to-noise images compared to wide-field and confocal schemes. However, due to the fact that up to this time 2PE can only be considered to be in its infancy, the advantages over other techniques are still being evaluated. Here, after a brief historical introduction, we focus on the basic principles of 2PE including fluorescence correlation spectroscopy. The major advantages and drawbacks of 2PE-based experimental approaches are discussed and compared to the conventional single-photon excitation cases. In particular we deal with the fluorescence brightness of most used dyes and proteins under 2PE conditions, on the optical consequences of 2PE, and the saturation effects in 2PE that mostly limit the fluorescence output. A complete section is devoted to the discussion of 2PE of fluorescent probes. We then offer a description of the central experimental issues, namely: choice of microscope objectives, two-photon excitable dyes and fluorescent proteins, choice of laser sources, and effect of the optics on 2PE sensitivity. An inevitably partial, but vast, overview of the applications and a large and up-to-date bibliography terminate the review.
As a conclusive comment, we believe that 2PE and related techniques can be considered as a mainstay of the modern biophysical research milieu and a bright perspective in optical microscopy
Numerical Modelling of the Aerodynamic Interference Between Helicopter and Ground Obstacles
No full textHelicopters are frequently operating in confined areas where the complex flowfields that develop in windy conditions may result in dangerous situations. Tools to analyse the interaction between rotorcraft wakes and ground obstacles are therefore essential. This work, within the activity of the GARTEUR AG22 "Forces on Obstacles in Rotor Wake ", attempts to assess numerical models for this problem. In particular, a helicopter operating in the wake of a building, one main rotor diameter above the ground, has been analysed. Tests performed at Politecnico di Milano provide a basis for comparison to validate CFD solvers. Afterward, unsteady simulations have been performed, with and without external wind. The helicopter has been modeled as steady and unsteady actuator disk and fully resolved blade simulations have been carried out to evaluate the accuracy of those simpler models. The final goal is to find the more efficient aerodynamic model that captures the wakes interaction so that real time coupled simulations can be made. Previous studies have already proved that the wake superposition technique cannot guarantee accurate results if the helicopter is close to the obstacle. The validity of that conclusion has been investigated in this work to determine the minimum distance between helicopter and building at which minimal wake interference occurs.Grant: The use of the data of the experiments by Gibertini et al. [13] is gratefully acknowledged
Primary succession on slopes exposed to intense erosion: the case of Vesuvius Grand Cone
No full textHarvesting Light To Produce Heat: Photothermal Nanoparticles for Technological Applications and Biomedical Devices
No full textThe photothermal properties of nanoparticles (NPs), that is, their ability to convert absorbed light into heat, have been studied since the end of the last century, mainly on gold NPs. In the new millennium, these studies have developed into a burst of research dedicated to the photothermal ablation of tumors. However, beside this strictly medical theme, research has also flourished in the connected areas of photothermal antibacterial surface coatings, gels and polymers, of photothermal surfaces for cell stimulation, as well as in purely technological areas that do not involve medical biotechnology. These include the direct conversion of solar light into heat, a more efficient sun-powered generation of steam and the use of inkjet-printed patterns of photothermal NPs for anticounterfeit printing based on temperature reading, to cite but a few. After an analysis of the photothermal effect (PTE) and its mechanism, this minireview briefly considers the antitumor-therapy theme and takes an in-depth look at all the other technological and biomedical applications of the PTE, paying particular attention to photothermal materials whose NPs have joined those based on Au
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