No abstract

(+)-2-Deoxyoryzalexin S (1), the nominal enantiomer of a diterpenoid isolated in Chile from Calceolaria species, was regio- and diastereoselectively synthesized from (+)-podocarpic acid. (+)-2-Deoxyoryzalexin S (1) was characterized also as its acetyl derivative, (+)-2, whose structure was confirmed by X-ray crystallographic analysis. Surprisingly, comparison of the data recorded for (+)-1 and (+)-2 and those reported in the literature for the Calceolaria isolated diterpenoid 1 and its derivative (-)-2 showed some differences, suggesting that the latter do not possess the proposed structures.

The evolution of the solar system and the origin of life remain some of the most intriguing questions for humankind. Addressing these questions experimentally is challenging due to the difficulty of mimicking environmental conditions representative for Early Earth and/or space conditions in general in ground-based laboratories. Performing experiments directly in space offers the great chance to overcome some of these obstacles and to possibly find answers to these questions. Exposure platforms in Low Earth Orbit (LEO) with the possibility for long-duration solar exposure are ideal for investigating the effects of solar and cosmic radiation on various biological and non-biological samples. Up to now, the Exobiology and space science research community has successfully made use of the International Space Station (ISS) via the EXPOSE facility to expose samples to the space environment with subsequent analyses after return to Earth. The emerging small and nanosatellite market represents another opportunity for astrobiology research as proven by the robotic O/OREOS mission, where samples were monitored in-situ, i.e. in Earth orbit. In this framework, the European Space Agency is developing a novel Exobiology facility outside the ISS. The new platform, which can host up to four different experiments, will combine the advantages of the ISS (long-term exposure, sample return capability) with near-real-time in-situ monitoring of the chemical/biological evolution in space. In particular, ultraviolet-visible (UV-Vis) and infrared (IR) spectroscopy were considered as key non-invasive methods to analyse the samples in situ. Changes in the absorption spectra of the samples developing over time will reveal the chemical consequences of exposure to solar radiation. Simultaneously, spectroscopy provides information on the growth rate or metabolic activities of biological cultures. The first quartet of experiments to be performed on-board consists of IceCold, OREOcube and Exocube (dual payload consisting of ExocubeChem and ExocubeBio). To prepare for the development of the Exobiology facility, ground units of the UV-Vis and IR spectrometers were studied, manufactured and tested as precursors of the flight units. The activity led to a modular in-situ spectroscopy platform able to perform different measurements (e.g. absorbance, optical density, fluorescence measurements) at the same time on different samples. We describe here the main features of the ground model platform, the verification steps, results and approach followed in the customization of commercial-off-the-shelf (COTS) modules to make them suitable for the space environment. The environmental tests included random and shock vibration, thermal vacuum cycles in the range −20°C to +40°C and irradiation of the components with a total dose of 1800 rad (18 Gy). The results of the test campaign consolidated the selection of the optical devices for the Exobiology Facility. The spectroscopic performance of the optical layout was tested and benchmarked in comparison with state-of-...

In aerospace applications the development of a reliable method of structural health monitoring (SHM) is one of the most important keys in maintaining the integrity and safety of structures, preventing catastrophic failure. The research program DEDALO aims at developing a real size UHTC-based prototype with a complex shape equipped with a SHM system for damage detection. A multidisciplinary approach has been adopted involving mechanical design, materials science, manufacturing processes and development of optical devices to detect strain and temperature on the as-produced UHTC articles. Former activities merged into the manufacturing of a prototype hot structure supplied with optical sensing nodes to perform a functional test at high temperature. This communication describes the preliminary findings of the project. A series of ZrB 2-SiC based compositions was studied adjusting type, concentration and granulometry of reinforcing phases and additives to further identify the optimal composition for the hot structure. The pressureless sintering technique was selected privileging a near-net-shape approach to reduce the manufacturing costs. A SHM system was developed using commercial high temperature Fiber optic Bragg Grating (FBG), for thermal monitoring, and custom silica-sapphire fiber optic strain sensor, based on Fabry-Pèrot configuration, allowing simultaneous and real time measurement of temperature and structural loads applied on the structure under investigation. A ceramic flexible structure was developed to ease sensor installation procedure on complex shape test articles. The fiber optic sensors interrogation system was developed based on a tunable laser source. Thermal and mechanical tests showed sensor robustness at high temperature and 0,6 μ as accuracy on strain measurement 0 togliere up to 800°C. Tile-shaped hot structures were manufactured, equipped with the prototype Structural Health Monitoring System (SHMS) and functionally tested at high temperature. The project will undergo a second iterative loop which foresees investigation on the final test article: a ZrB 2-SiC based composite hollow tip.

In aerospace applications the development of a reliable method of structural health monitoring (SHM) is one of the most important keys in maintaining the integrity and safety of structures, preventing catastrophic failure. The research program DEDALO aims at developing a real size UHTC-based prototype with a complex shape equipped with a SHM system for damage detection. A multidisciplinary approach has been adopted involving mechanical design, materials science, manufacturing processes and development of optical devices to detect strain and temperature on the as-produced UHTC articles. Former activities merged into the manufacturing of a prototype hot structure supplied with optical sensing nodes to perform a functional test at high temperature. This communication describes the preliminary findings of the project. A series of ZrB-SiC based compositions was studied adjusting type, concentration and granulometry of reinforcing phases and additives to further identify the optimal composition for the hot structure. The pressureless sintering technique was selected privileging a near-net-shape approach to reduce the manufacturing costs. A SHM system was developed using commercial high temperature Fiber optic Bragg Grating (FBG), for thermal monitoring, and custom silica-sapphire fiber optic strain sensor, based on Fabry-Pèrot configuration, allowing simultaneous and real time measurement of temperature and structural loads applied on the structure under investigation. A ceramic flexible structure was developed to ease sensor installation procedure on complex shape test articles. The fiber optic sensors interrogation system was developed based on a tunable laser source. Thermal and mechanical tests showed sensor robustness at high temperature and 0,6 µε as accuracy on strain measurement 0 togliere up to 800°C. Tile-shaped hot structures were manufactured, equipped with the prototype Structural Health Monitoring System (SHMS) and functionally tested at high temperature. The project will undergo a second iterative loop which foresees investigation on the final test article: a ZrB2-SiC based composite hollow tip.