In the framework of a study on the aging phenomena of textiles we used Raman spectral mapping to analyze changes in the chemical bonds of cellulose of flax fabrics exposed to ultraviolet (UV) radiation in air, and extreme ultraviolet (EUV) radiation in vacuum. Our results show that both UV and EUV produce photolysis of cellulose bonds, which in turn triggers photochemical oxidation and dehydration, in a kind of “accelerated aging” and oxidative degradation of flax. In particular, we detected the formation of a large number of carboxyl and carbonyl groups, which, when conjugated, act as chromophores and give flax a yellowish hue. Remarkably, the mapping of Raman spectra makes it possible to identify the relative weights of molecular reactions responsible for the generation of oxidized groups and aging of cellulose. In particular, the comparison of spatially-resolved Raman spectra after irradiations UV in air and EUV in vacuum provides direct and quantitative evidence of the role of oxygen in the molecular changes leading to flax aging due to UV illumination. As an example, we found that atmospheric oxygen does not affect the change of the degree of polymerization of cellulose nor the formation of carboxyl and carboxyl groups. These results help to assess the possible benefit, if any, of preserving and exposing ancient cellulosic cloths in an inert, oxygen-free atmosphere.

In the field of book heritage, it is important to develop cleaning/disinfecting treatments that can slow down the degradation of paper to prevent evident and irreversible damage. The objectives of the cleaning treatments are to remove external contaminants and oxidation and decomposition products of the paper, but these processes must not modify the unique characteristics of the book heritage resulting in irreversible changes in the structure of the paper. Recently, several innovative cleaning treatments were developed with the aim of being minimally invasive; however, to assess the effect of these treatments on paper, it is necessary to use a diagnostic non-destructive, rapid, and affordable process. In previous work, we used surface scanning Raman spectroscopy to develop a diagnostic protocol able to follow the aging processes of the paper, discriminating between hydrolysis and oxidation. In this paper, we applied this protocol to study the action of different types of treatments (hydrogel and EUV irradiation), evaluating both their effectiveness and impact on paper parameters. The results reported here demonstrate that the developed in operando diagnostic procedure can follow the changes in the paper structure comparing them to the variability due to the intrinsic inhomogeneity of paper, without sample contact in a rapid and effective way.

The interest of aerospace and automotive fields in the improvement of energy absorption properties of composite materials has stimulated researchers to design new typologies of cores of sandwich -structures under impact events. In this work, a sandwich structure based on pre -stressed bistable carbon fibre composite core is proposed. The core, named Circular Prestressed Carbon Core (CPCC), takes advantage of the asymmetric fibres orientation and the bistability-concept to enhance energy dissipation and reduce the damage extension during impacts. The impact campaign was conducted both experimentally and numerically to analyse the mechanical properties of the core and to study the contribution of the residual stresses. Experimental results were compared with an aerospace -grade aluminium honeycomb -core and a not -prestressed version of the core. Results proved its unique impact characteristics, showing, an improvement of the maximum -force up to 171 % and 23 % in comparison with aluminium honeycomb and not -prestressed CPCC, respectively. The specific properties of the CPCC were considerably higher than the aluminium sandwich, with peak force values up to +75 %, displacement reduced up to -71 %, and non-destructive evaluation (NDE) test showed a reduction of the projected damaged area by similar to 20 %. These results demonstrates that the CPCC structure constitutes a novel high-performance sandwich core for improved impact resistance.

In this paper, an overview of the potentiality of Arduino boards is presented, together with a description of the Arduino interfacing with light multi-sensors. These sensors can be arranged in linear arrays or in a matrix configuration (CCD or CMOS type cameras) and are equipped with tens, hundreds, or even thousands of elements whose sizes range from a few microns to tens of microns. The use of these sensors requires electronics that have high time accuracy, since they work through regular pulses sent by an external source and, furthermore, have the ability to digitize and store voltage signals precisely and quickly. We show that, with the appropriate settings, a simple Arduino board can handle both 1D and 2D optical sensors. Finally, we describe a solar compass made with such a board coupled to one of the tested optical array sensors that is capable of providing the north direction with a very high degree of accuracy.

We present the electrical and optical design, assembling, and thorough experimental characterization of two compact arrays of short-wavelength ultraviolet (UV-C) light-emitting diodes (LEDs) suitable for near-field irradiation. Through a combination of technical expedients, we have achieved effective thermal management such that long-lasting irradiations are possible without appreciable deterioration of UV-C emission. We successfully used these compact UV-C LED arrays for long lasting irradiation tests aimed at generating the biosynthesis of defensive metabolites that enhance the resistance of plants and fruits to pathogen attacks. Finally, we comment on the possibility of implementing these compact UV-C sources on robotic systems to make an automated device suitable to reduce pesticide use in agricultural crops.

Mechanical properties of composite laminates are directly affected by the level of porosity of the part. Therefore, it is important to ensure that an adequate air debulking is provided during the manufacturing in order to obtain high quality products. The use of ultrasonic waves during the hand lay-up of prepreg layers can enhance this step. In a previous work we have demonstrated that this technique, named ultrasonic consolidation (UC), can lead to a large reduction in terms of manufacturing time and improvements of the Interlaminar Shear Strength (ILSS) of the final part. In this work, a model is proposed to analytically describe the influence of the ultrasonic stimulation on the air flux through the material and optimise the procedure, showing how the use of ultrasonic waves significantly increases the net air flow rate, particularly for small radius voids. The study provided some guidelines for the optimisation of the process parameters such as the frequency and location of the transducers. The efficiency of the method was experimentally validated by manufacturing several samples using UC debulking procedure with three exposition times (5-10-15 min). Microscope images showed a large decrement (up to 96%) of the voids projected area in samples section in comparison with reference. Flexural and Charpy impact properties were evaluated through mechanical tests, showing properties comparable to the reference samples, with improvements in terms of flexural modulus (up to 9%). Results from the analytical study and experimental tests indicate that the UC process is a reliable debulking procedure for the hand lay-up of prepreg that largely reduces manufacturing time and voids content, leading to improvements of the mechanical properties of the final part.

Ultraviolet C-band (UV-C) sources based on LED arrays, for near-field irradiation purposes, have been designed, realized, and thoroughly characterized both from an optical and a thermal point of view. Here we report the main theoretical and experimental results and discuss the preliminary applications of these sources.

In this work, an experimental preliminary assessment on the fatigue behavior of nanomodified composite coupons has been attempted. Comparisons between the fatigue life of epoxy resin/carbon fiber neat coupons and epoxy resin/carbon fiber specimens reinforced with nanoparticles have been carried out. Tensile, compressive, and in-plane shear samples have been manufactured according to ASTM D3039, ASTM D3410, and ASTM D3518 standards, respectively. The coupons, both with neat and nanomodified epoxy resin, have been tested under tension-tension, compression-compression and in-plane shear fatigue loading conditions to understand the effect of the nanoparticles' addition on the fatigue behavior of thermosetting epoxy resin.

We have developed an app, named Sunpass, that is able to convert every smartphone into a solar compass. Sunpass uses input data from the smartphone sensors, calculates the Sun position, and elaborates data to give the desired information. The azimuth values measured by a smartphone equipped with Sunpass show a typical accuracy of 0.5°, which is limited by camera aberrations and misalignment of both accelerometer and CCD camera of the smartphone. In this paper, we show that both accuracy and reliability in azimuth measurements can be improved by a specific calibration procedure and a dedicated mechanical tool. We obtained a remarkable accuracy better than 0.06° on the single azimuth measurements, which improves to 0.03° on the average of eight measurements.

We exploit a very accurate electronic solar compass used for the first time in archaeology, to measure the orientation of structures at the Tiberius' Cave, which is adjacent to the Villa of the Roman emperor Tiberius located nearby the National Archaeological Museum in Sperlonga, Italy. The measures are aimed at verifying whether Tiberius' Cave artefacts were aligned to specific astronomical events, connected to the apparent motion of the Sun. The experimental results suggest the intentional alignment of two niches to provide an accurate reference during the sunset on the day of the winter solstice at the time of Tiberius. (C) 2022 Elsevier Masson SAS. All rights reserved.

Development of high-performance sandwich structures is particularly attractive for aerospace applications, where novel lighter materials and structures are object of extensive research. This work is focused on the design of a new high-performance Carbon FRP core as alternative to traditional periodic prismatic ones. The innovative core is designed as a 2D close-packing pattern of circular cells and manufactured by connecting pre-preg corrugated laminates in specific locations. The corrugated laminates are layered following an asymmetric sequence in order to generate residual thermal stresses within the core to enhance energy absorption and compressive properties. The distribution of the residual thermal stress within the core was numerically studied with a finite element model of the unit cell, in order to prove the positive contribution of the asymmetric layup on the mechanical properties and study the failure mechanisms of the unit-cell. Composite core samples were manufactured, and their mechanical properties were experimentally evaluated through compression, both out-of-plane and in-plane, and beam flexure tests. Results were compared in terms of specific properties with traditional aluminium honeycomb core, showing large increments of specific compressive strength (+84.6%), in-plane compressive modulus (over +500%), Specific Energy Absorption (+145%) and shear (>20%). The FEM model was validated against experimental compressive results, showing an error below 10%. The results show that the core is suitable for applications in novel high-performance sandwich structures, leading to numerous advantages in comparison to traditional cores, such as higher specific properties, manufacturability of complex sandwich structures and higher adhesion and compatibility with CFRP skins.

Debulking of prepreg (pre-impregnated resin system) layers during hand lay-up manufacturing of carbon fibre reinforced polymers (CFRP) is a key-step to reduce air content and maximise the mechanical properties of the final product. Debulking is usually performed using vacuum-bag cycles of 10-15 min applied after the lay-up of every three or five prepreg layers, leading to a considerable time-consuming process. In this work, the use of ultrasonic stimulation during vacuum is studied to improve the efficiency of the debulking process and reduce the number of operations in order to decrease the overall manufacturing time. Three CFRP laminates were laid-up using the proposed ultrasonic consolidation (UC) with three different exposition times (5, 10 and 15 min) and cured in autoclave. The UC debulking process consists in a vacuum cycle with ultrasonic waves sent to the uncured material through an ultrasonic transducer. In order to evaluate the efficiency of this process interlaminar shear strength (ILSS) and in-plane compressive properties were tested. Experimental results show for 15 min compressive properties comparable with the ones obtained from reference samples manufactured using the traditional debulking technique, and high improvements in terms of ILSS (>20%). Therefore, UC debulking process can be used during hand lay-up of prepreg in order to improve the interlaminar properties of the final part and reduce the debulking time by over 85%. (C) 2019 Elsevier Ltd. All rights reserved.

The aerospace industry?s current focus on recyclable materials and low-cost processes has accelerated research and implementation of thermoplastics matrix composites (TPC). In the last decades, researchers have researched weldability of these materials as a valid alternative to conventional mechanical fastening and adhesives, for improving the strength of the joint. Automatic induction welding of carbon fiber TPCs is one of the most promising techniques due to its numerous benefits, such as elevated energy efficiency and highly localised heat. As for all the manufacturing techniques, the importance of efficiently detecting the presence of defects during TPCs welding has pushed the need for automated real-time non-destructive evaluation (NDE) systems. This paper focuses on the development of an efficient NDE technique able to detect the presence of alterations and defects in real-time during the welding process. This technique relies on Infrared (IR) active thermography inspections performed using the induction welding heat as the source and an undamaged baseline methodology to detect differences in the heat field. The procedure was experimentally analysed by means of an apparatus capable of automatic welding of samples, performing the real-time NDE during the process. Results show the efficiency of the method to localise the damaged area and characterise the defects during the welding. The undamaged baseline methodology was proven to better clarify shape and location of defects, allowing for an efficient detection of damaged samples and areas where more detailed inspections can be performed after the welding process by means of the same IR apparatus.

The accurate determination of the azimuth of a given direction, e.g., the true (geographic) North, is of fundamental importance in many fields. Just as few examples, it guides buildings construction in civil engineering, supports environmental and cartographic surveys, allows the correct positioning and stability control of concentrating solar power plants, as well as of airport installations, provides the geographic North reference for geomagnetic measurements, contributes to the interpretation of the orientation choices of ancient constructions in archeoastronomy, can be the primary benchmark to calibrate other compasses or gyroscopes. When aiming at reaching azimuth measurements with accuracies well below 1°, magnetic compasses are unreliable: firstly, they indicate the magnetic North rather than the geographic one; secondly, they are heavily influenced by possible surrounding ferromagnetic items.

The accurate assessment of the azimuth of a given direction as, e.g., the geographic North, is of utmost importance in many fields. The electronic solar compass patented by ENEA achieves an accuracy of 0.01 degrees, it is up to 100 times cheaper than instruments having similar accuracy (GPS, gyros, ...), and it is also very fast in answering (few seconds). It is based on a simple but effective optical system to capture the Sun direction, and on an analytical algorithm to provide the Sun position. The ENEA solar compass has been tested and used in many circumstances, e.g., for mapping surveys, to align concentrating solar mirrors, and for orientation measurements of structures in archaeological sites. We obtained notable results, together with INGV, in magnetic declination measurements in Antarctica. Finally, we moved the ENEA solar compass algorithm to smartphones, enabling their use as orienteering devices.

The growing importance of reliable, rapid, and non-contact non-destructive evaluation (NDE) of parts/structures either during manufacturing or maintenance operations has promoted the development of real-time, automated, and in-situ methods. The major driving factors for automation of traditional NDE techniques, such as thermographic imaging methods, are savings in cost and time. In this work a novel real-time low-cost automated heating and cooling thermographic system is developed. The system implements a novel cooling mechanism along with heating elements to provide precise control of heating and cooling of inspected structures and was built using low-cost components. A carbon fibre reinforced plastic (CFRP) composite sample with flat bottom holes (FBH) was used to evaluate the effectiveness of the system. This system is coupled with a model to provide insights into system optimisation and show the potential that highly flexible inspection systems can be tailored for specific industrial requirements. The modelled heating and cooling process was important in determining which parts of the thermal profile would provide the best results. The system was assessed using three heating/cooling profiles: heating only (HO), cooling only (CO) and heating and cooling (HC). The results show that each method was equally as good as determining defects in the tested structure, with HC having the potential to outperform the others if optimised.

In the last decades, advanced thermoplastics matrix composites (TPCs) were recognised as a valid alternative to thermosetting matrices for many advanced applications. One of the advantages in the use of TPCs is the capability to perform fusion bonding which avoids the use of external joints. Induction welding of carbon fiber reinforced TPCs has gained large interest thanks to the minimum surface preparation required, high efficiency and capability to localise heat at the welding surface. This study relies on a thermal wave technique for the in-situ and real-time evaluation of defects during electromagnetic induction welding of TPCs. The technique is based on a methodology which analyses thermal images acquired in real-time during the welding process to reveal discontinuities from variations in heat distribution. Furthermore, the proposed apparatus is used to conduct post-welding inspections on the damaged area for more detailed defects characterisation. An induction welding device is used to perform the bonding process and different kinds of defects were tested and evaluated. Real-time thermal images of the welding process of TCP samples were obtained by using Infrared (IR) cameras. The recorded data were elaborated and used to locate and evaluate the different kinds of damaged samples. A post-welding analysis of a detected damaged region was performed using heating parameters optimised for the thermography scan. Results show the reliability of the method in detecting and characterising the presence of defects during the welding process using the available heating source without altering the process parameters.

a solar compass is presented, which determines the true North direction with an accuracy of 0.01°. It is compact, fast and low-cost and can also drive a solar panel for continuously aiming at the Sun

This contribution to ECPD2019 is dedicated to the memory of Anatoly Faenov. During a period of approximately thirteen years 1994–2006, Anatoly and his wife Tatiana Pikuz (simply “Tania” for friends), accepting the frequent invitations of the National Institute for Nuclear Physics (INFN) and of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), cooperated with many Italian research laboratories dedicated to EUV and soft X-ray generation, spread in different towns (L'Aquila, Frascati, Milano, Padova, Pisa, Roma, etc.). In spite of the fact that they could stay in Italy only about one or two months per year, their activity was so intense that more than 50 peer- reviewed publications were generated from their experimental and theoretical work (just considering only the results obtained at L'Aquila and Tor Vergata—Rome Universities and at the ENEA Research Center of Frascati), without mentioning the cultural atmosphere that they stimulated in the field of Science and Humanity. The numerous experimental spectra obtained at ENEA by means of their spherically bent mica spectrometers, together with the corresponding theoretical simulations performed in Moscow, allowed to study the changing role of different excitations mechanisms for various plasma conditions, and to characterize at best the ENEA laser-plasma source for different applications: polychromatic and monochromatic micro-radiography of dried biological samples at 1 keV, soft X-ray contact microscopy (SXCM) of living cells in the water-window spectral region, spectroscopy of hollow atoms, etc. In this memorial paper, the main results of biological samples imaging on lithium fluoride (LiF) detectors, obtained with the ENEA and Tor Vergata University laser-plasma sources, are presented. In particular, the improvement of the micro-radiography and of the SXCM techniques obtained after moving from photoresist detectors and photographic films to lithium fluoride (LiF) detectors are discussed, for both dried and wet biological samples.

We report micro-Raman spectroscopy, High-Resolution Scanning Electron Microscopy (HR-SEM) and Atomic Force Microscopy (AFM) investigation of changes in CVD grown single -layer graphene structure induced by Extreme UltraViolet (EUV) irradiation. We found that the exposures at doses up to 200 mJ/cm2 result in the appearance of D and D′ bands related to defects in graphene lattice. The evolution of D and G band intensity ratio follows the first stage of amorphization trajectory, which indicates transformation of pristine graphene to nano-crystalline form. Raman mapping demonstrated that the defects are localized only within the EUV irradiated areas, with a density controlled by the EUV dose.