Adaptive and Online Health Monitoring System for Autonomous Aircraft

Good situation awareness is one of the key attributes required to maintain safe flight, especially for an Unmanned Aerial System (UAS). Good situation awareness can be achieved by incorporating an Adaptive Health Monitoring System (AHMS) to the aircraft. The AHMS monitors the flight outcome or flight behaviours of the aircraft based on its external environmental conditions and the behaviour of its internal systems. The AHMS does this by associating a health value to the aircraft's behaviour based on the progression of its sensory values produced by the aircraft's modules, components and/or subsystems. The AHMS indicates erroneous flight behaviour when a deviation to this health information is produced. This will be useful for a UAS because the pilot is taken out of the control loop and is unaware of how the environment and/or faults are affecting the behaviour of the aircraft. The autonomous pilot can use this health information to help produce safer and securer flight behaviour or fault tolerance to the aircraft. This allows the aircraft to fly safely in whatever the environmental conditions. This health information can also be used to help increase the endurance of the aircraft. This paper describes how the AHMS performs its capabilities

Siloxane crosslinks with dynamic bond exchange enable shape programming in liquid-crystalline elastomers.

Liquid crystalline elastomers (LCE) undergo reversible shape changes in response to stimuli, which enables a wide range of smart applications, in soft robotics, adhesive systems or biomedical medical devices. In this study, we introduce a new dynamic covalent chemistry based on siloxane equilibrium exchange into the LCE to enable processing (director alignment, remolding, and welding). Unlike the traditional siloxane based LCE, which were produced by reaction schemes with irreversible bonds (e.g. hydrosilylation), here we use a much more robust reaction (thiol-acrylate/thiol-ene 'double-click' chemistry) to obtain highly uniform dynamically crosslinked networks. Combining the siloxane crosslinker with click chemistry produces exchangeable LCE (xLCE) with tunable properties, low glass transition (-30 °C), controllable nematic to isotropic transition (33 to 70 °C), and a very high vitrification temperature (up to 250 °C). Accordingly, this class of dynamically crosslinked xLCE shows unprecedented thermal stability within the working temperature range (-50 to 140 °C), over many thermal actuation cycles without any creep. Finally, multiple xLCE sharing the same siloxane exchangeable bonds can be welded into single continuous structures to allow for composite materials that sequentially and reversibly undergo multiple phase transformations in different sections of the sample.ERC H202

Catalytic Control of Plastic Flow in Siloxane-Based Liquid Crystalline Elastomer Networks.

Liquid crystalline elastomer networks cross-linked by dynamic covalent bonds (xLCE) have the ability to be (re)processed during the plastic flow. However, the current bond-exchange strategies that are used to induce plastic flow in xLCE lack the efficient method to control the elastic-plastic transition. Here we describe a straightforward method to manipulate the transition to plastic flow via the choice of catalyst in xLCE cross-linked by siloxane. The nature and the amount of catalyst have a profound effect on the elastic-plastic transition temperature, and the stress relaxation behavior of the network. The temperature of fast plastic flow and the associated bond-exchange activation energy varied from 120 °C and 83 kJ/mol in the "fastest" exchange promoted by triazobicyclodecene (TBD) to 240 °C and 164 kJ/mol in the "slowest" exchange with triphenylphosphine (PPH), with a range of catalysts in between. We have identified the optimum conditions for programming an aligned monodomain xLCE, high programming temperature (230 °C) and low nematic to isotropic transition (60 °C), to achieve thermally and mechanically stable actuators.European Research Council H202

Signalizacija gena za receptor vitamina D, enzim 1 alfa-hidroksilazu i RANTES u mliječnih krava s hipokalcemijom

The aim of the current study focused on screening the signal of the vitamin D receptor (VDR), 1-alpha-hydroxylase (1α-OHase) enzyme, and chemokine regulated on activation, normal T-cell expressed and secreted (RANTES) genes in dairy cows with hypocalcaemia. A sample of 120 dairy cows (20 dairy cows per herd) in the transition period was studied. Blood samples were drawn from the selected dairy cows for both biochemical and molecular analysis. In cows with subclinical and clinical hypocalcemia, there was a significant (P<0.05) down-regulation of both VDR and RANTES genes, whereas there was a significant (P<0.05) up-regulation of the 1α-OHase enzyme. Moreover, there was a significant (P<0.05) increase in the levels of glucose, parathyroid hormone (PTH), sodium (Na), and chloride (Cl). Furthermore, there was a significant (P<0.05) decrease in the levels of phosphorous and potassium (K). On the animal level, there was a significant association between the expression pattern of the VDR gene and the cows’ breed, the cows’ age, parity number, body condition score, and history of previous transition period disorders. The increase in both the expression of 1α-OHase enzyme and the level of each of PTH, glucose, Na, and Cl in the serum were significant risk factors for the decreased expression of the VDR gene. Likewise, the decrease in both the expression of the RANTES gene and the level of calcium (Ca) and phosphorous in the serum were significant risk factors for decreased expression of the VDR gene. This study revealed that the expression of VDR, 1α-OHase enzyme, and RANTES genes in the blood was greatly affected in dairy cows with hypocalcemia, indicating the need for an extra dose of vitamin D to maintain the normal level of Ca in the blood, especially during periods of high need. Hence, this study provides an insight into the role of vitamin D and its related enzymes in promoting the productivity of dairy cows, especially during the critical production periods.Cilj ovog istraživanja bio je nadzor genskog signala za receptor vitamina D (VDR), enzim 1-alfa-hidroksilazu (1 α-OHase) i kemokin (Regulated on Activation Normal T-cell Expressed and Secreted – RANTES) u mliječnih krava s hipokalcemijom. Uzorci za biokemijske i molekularne analize prikupljeni su od 120 mliječnih krava (20 krava po stadu), tijekom prijelaznog razdoblja. U krava s subkliničkom i kliničkom hipokalcemijom utvrđena je znakovita (P < 0,05) podregulacija gena VDR i RANTES, te znakovita (P < 0,05) nadregulacija enzima 1-α-Ohaza. Nadalje, u tih životinja došlo je do znakovitog (P < 0,05) povećanja razina glukoze, paratireoidnog hormona (PTH), natrija (Na) i klorida (Cl), te znakovitog (P < 0,05) smanjenja razina fosfora (P) i kalija (K). Uvažavajući različite osobine životinja utvrđena je znakovita povezanost između izražajnosti VDR gena i pasmine krava, dobi krava, redoslijeda teljenja, ocjene tjelesne kondicije te prethodnih poremećaja u prijelaznom razdoblju. Povećanje, s jedne strane ekspresije za enzim 1 α-OHase i s druge strane razine PTH, glukoze, Na i Cl u serumu, dovelo je do znakovitog rizika za smanjenu ekspresiju VDR gena. Isto tako, smanjenje ekspresije gena RANTES i razine kalcija (Ca) i fosfora (P) u serumu bili su značajni čimbenici rizika za smanjenu ekspresiju gena VDR. Ovo je istraživanje pokazalo da je na ekspresiju gena VDR, 1 α-Ohaza i RANTES u krvi mliječnih krava uvelike utjecala hipokalcemija, što upućuje na potrebu dodatne doze vitamina D kako bi se održala normalna razina Ca u krvi, osobito u zahtjevnim razdobljima visoke proizvodnje. Stoga ova studija daje uvid u ulogu vitamina D i s njim povezanih enzima u poboljšanju produktivnosti mliječnih krava, posebno u kritičnim razdobljima proizvodnje

Dynamic Semicrystalline Networks of Polypropylene with Thiol-Anhydride Exchangeable Crosslinks.

Thermoplastic polyolefins (TPOs) crosslinked by dynamic covalent bonds (xTPOs) have the potential to be the most utilized class of polymer in the world, with applications ranging from household and automotive to biomedical devices and additive manufacturing. xTPO combines the benefits of thermoplastics and thermosets in a "single material" and potentially avoids their shortcomings. Here, we describe a new two-stage reaction extrusion strategy of TPOs with a backbone consisting of inert C-C bonds (polypropylene, PP), and thiol-anhydride, to dynamically crosslink PP through thiol-thioester bond exchange. The degree of PP crosslinking determines the rubber plateau modulus above the melting point of the plastic: the modulus at 200 °C increases from zero in the melt to 23 kPa at 6% crosslinking, to 60 kPa at 20%, to 105 kPa at 40%. The overall mechanical strength of the solid xTPO plastic is 25% higher compared to the original PP, and the gel fraction of xTPO reaches 55%. Finally, we demonstrate that the crosslinked xTPO material is readily reprocessable (recycled, remolded, rewelded, and 3D printed)

Rates of transesterification in epoxy-thiol vitrimers.

Vitrimers, an important subset of dynamically crosslinked polymer networks, have many technological applications for their excellent properties, and the ability to be re-processed through plastic flow above the so-called vitrification temperature. We report a simple and efficient method of generating such adaptive crosslinked networks relying on transesterification for their bond exchange by utilising the 'click' chemistry of epoxy and thiols, which also has the advantage of a low glass transition temperature. We vary the chemical structure of thiol spacers to probe the effects of concentration and the local environment of ester groups on the macroscopic elastic-plastic transition. The thermal activation energy of transesterification bond exchange is determined for each chemical structure, and for a varying concentration of catalyst, establishing the conditions for the optimal, and for the suppressed bond exchange. However, we also discover that the temperature of elastic-plastic transition is strongly affected by the stiffness (dynamic rubber modulus) of the network, with softer networks having a much lower vitrification temperature even when their bond-exchange activation energy is higher. This combination of chemical and physical control factors should help optimise the processability of vitrimer plastics.ERC h2020 AdG "APRA" (786659)