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Transition Metal Carbides (TMCs) catalysts for gas phase CO2 upgrading reactions: a comprehensive overview
No full textIncreasing demand for CO2 utilization reactions and the stable character of CO2 have motivated the interest in developing highly active, selective and stable catalysts. Precious metal catalysts have been studied extensively due to their high activities, but their implementation for industrial applications is hindered due to their elevated cost. Among the materials which have comparatively low prices, transition metal carbides (TMCs) are deemed to display catalytic properties similar to Pt-group metals (Ru, Rh, Pd, Ir, Pt) in several reactions such as hydrogenation and dehydrogenation processes. In addition, they are excellent substrates to disperse metallic particles. Hence, the unique properties of TMCs make them ideal substitutes for precious metals resulting in promising catalysts for CO2 utilization reactions. This work aims to provide a comprehensive overview of recent advances on TMCs catalysts towards gas phase CO2 utilization processes, such as CO2 methanation, reverse water gas shift (rWGS) and dry reforming of methane (DRM). We have carefully analyzed synthesis procedures, performances and limitations of different TMCs catalysts. Insights on material characteristics such as crystal structure and surface chemistry and their connection with the catalytic activity are also critically reviewed
Two Ultra-faint Milky Way Stellar Systems Discovered in Early Data from the DECam Local Volume Exploration Survey
No full textWe report the discovery of two ultra-faint stellar systems found in early data from the DECam Local Volume Exploration survey (DELVE). The first system, Centaurus I (DELVE J1238–4054), is identified as a resolved overdensity of old and metal-poor stars with a heliocentric distance of , a half-light radius of , an age of , a metallicity of , and an absolute magnitude of . This characterization is consistent with the population of ultra-faint satellites and confirmation of this system would make Centaurus I one of the brightest recently discovered ultra-faint dwarf galaxies. Centaurus I is detected in Gaia DR2 with a clear and distinct proper motion signal, confirming that it is a real association of stars distinct from the Milky Way foreground; this is further supported by the clustering of blue horizontal branch stars near the centroid of the system. The second system, DELVE 1 (DELVE J1630–0058), is identified as a resolved overdensity of stars with a heliocentric distance of , a half-light radius of , an age of , a metallicity of , and an absolute magnitude of , consistent with the known population of faint halo star clusters. Given the low number of probable member stars at magnitudes accessible with Gaia DR2, a proper motion signal for DELVE 1 is only marginally detected. We compare the spatial position and proper motion of both Centaurus I and DELVE 1 with simulations of the accreted satellite population of the Large Magellanic Cloud (LMC) and find that neither is likely to be associated with the LMC
Profitability analysis of a novel configuration to synergize Biogas Upgrading and Power-to-Gas"
No full textDeflection of the hypervelocity stars by the pull of the Large Magellanic Cloud on the Milky Way
No full textStars slingshotted by the supermassive black hole at the Galactic centre escape from
the Milky Way so quickly that their trajectories are almost straight lines. Previous
works have shown how these `hypervelocity stars' (stars moving faster than the local
Galactic escape speed) are subsequently de
ected by the gravitational field of the Milky
Way and the Large Magellanic Cloud (LMC), but have neglected to account for the reflex motion of the Milky Way in response to the y-by of the LMC. A consequence
of this motion is that the hypervelocity stars we see in the outskirts of the Milky Way today were ejected from where the Milky Way centre was hundreds of millions of years
ago. This change in perspective causes large apparent de
ections of several degrees in
the trajectories of the hypervelocity stars. We quantify these deflections by simulating the ejection of hypervelocity stars from an isolated Milky Way (with a spherical or flattened dark matter halo), from a fixed-in-place Milky Way with a passing LMC,
and from a Milky Way which responds to the passage of the LMC, finding that LMC passage causes larger de
ections than can be caused by a
attened Galactic dark matter halo in �CDM. The 10 �as y
Evaluation of a Novel Liquid Fiducial Marker, BioXmark®, for Small Animal Image-Guided Radiotherapy Applications
No full textBioXmark®(Nanovi A/S, Denmark) is a novel fiducial marker based on a liquid, iodine-basedand non-metallic formulation. BioXmark®has been clinically validated and reverse translated topreclinical models to improve cone-beam CT (CBCT) target delineation in small animal image-guidedradiotherapy (SAIGRT). However, in phantom image analysis andin vivoevaluation of radiobiologicalresponse after the injection of BioXmark®are yet to be reported. In phantom measurements wereperformed to compare CBCT imaging artefacts with solid fiducials and determine optimum imagingparameters for BioXmark®.In vivostability of BioXmark®was assessed over a 5-month period, andthe impact of BioXmark®onin vivotumour response from single-fraction and fractionated X-rayexposures was investigated in a subcutaneous syngeneic tumour model. BioXmark®was stable, welltolerated and detectable on CBCT at volumes≤10μL. Our data showed imaging artefacts reduced byup to 84% and 89% compared to polymer and gold fiducial markers, respectively. BioXmark®wasshown to have no significant impact on tumour growth in control animals, but changes were observedin irradiated animals injected with BioXmark®due to alterations in dose calculations induced by thesharp contrast enhancement. BioXmark®is superior to solid fiducials with reduced imaging artefactson CBCT. With minimal impact on the tumour growth delay, BioXmark®can be implemented inSAIGRT to improve target delineation and reduce set-up error
Vasorelaxing Activity of Stilbenoid and Phenanthrene Derivatives from Brasiliorchis porphyrostele: Involvement of Smooth Muscle CaV1.2 Channels
No full textFive compounds, 3,4’-dihydroxy-3’,5,5’-trimethoxydihydrostilbene, 1, 3,4'-dihydroxy-3',5'-dimethoxydihydrostilbene, 2, 3,4'-dihydroxy-5,5'-dimethoxydihydrostilbene, 3, 9,10-dihydro-2,7-dihydroxy-4,6-dimethoxyphenanthrene, 4, and the previously unreported 1,2,6,7-tetrahydroxy-4-methoxyphenanthrene, 5, were isolated from the South American orchid, Brasiliorchis porphyrostele. An in depth analysis of their vascular effects was performed on in vitro rat aorta rings and tail main artery myocytes. Compounds 1-4 were shown to possess vasorelaxant activity on rings pre-contracted by the α1 receptor agonist phenylephrine, the CaV1.2 stimulator (S)-(-)-Bay K 8644, or depolarised with high K+ concentrations. However, compound 5 was active solely on rings stimulated by 25 mM but not 60 mM K+. The spasmolytic activity of compounds 1 and 4 was significantly affected by the presence of an intact endothelium. The KATP channel blocker glibenclamide and the KV channel blocker 4-aminopyridine significantly antagonised the vasorelaxant activity of compounds 4 and 1, respectively. In patch-clamp experiments, compounds 1-4 inhibited Ba2+ current through CaV1.2 channels in a concentration-dependent manner, whereas neither compound 4 nor compound 1 affected K+ currents through KATP and KV channels, respectively. The present in vitro, comprehensive study demonstrates that Brasiliorchis porphyrostele may represent a source of vasoactive agents potentially useful for the development of novel antihypertensive agents that has now to be validated in vivo in animal models of hypertension
Structure of high-lying levels populated in the ⁹⁶Y → ⁹⁶Zr β decay
No full textThe nature of Jπ=1− levels of 96Zr below the β-decay Qβ value of 96Y has been investigated in high-resolution γ-ray spectroscopy following the β decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from β decay allow the absolute E1 excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of 1− levels below the Qβ value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the 96Ygs β decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum
IoT-Stream: A Lightweight Ontology for Internet of Things Data Streams and Its Use with Data Analytics and Event Detection Services
No full textWith the proliferation of sensors and IoT technologies, stream data are increasingly stored and analysed, but rarely combined, due to the heterogeneity of sources and technologies. Semantics are increasingly used to share sensory data, but not so much for annotating stream data. Semantic models for stream annotation are scarce, as generally, semantics are heavy to process and not ideal for Internet of Things (IoT) environments, where the data are frequently updated. We present a light model to semantically annotate streams, IoT-Stream. It takes advantage of common knowledge sharing of the semantics, but keeping the inferences and queries simple. Furthermore, we present a system architecture to demonstrate the adoption the semantic model, and provide examples of instantiation of the system for different use cases. The system architecture is based on commonly used architectures in the field of IoT, such as web services, microservices and middleware. Our system approach includes the semantic annotations that take place in the pipeline of IoT services and sensory data analytics. It includes modules needed to annotate, consume, and query data annotated with IoT-Stream. In addition to this, we present tools that could be used in conjunction to the IoT-Stream model and facilitate the use of semantics in IoT
Micro-mobilities in Curated Spaces: Agency, Autonomy and Dwelling in Visitor Experiences of Augmented Reality in Arts and Heritage
No full textMobile technologies are transforming the ways in which we experience arts and heritage sites, and galleries and museums are facing increased pressure to provide stimulating, alternative technology-based solutions for enriching visitor experiences. Focusing on the opportunities afforded by augmented reality (AR), this paper critiques the role this technology plays in providing visitors the opportunity to experience art and exhibitions through a series of dynamic, small-scale micro-mobilities. We propose that AR creates curated spaces of mobility in galleries and museums and in doing so, visitors become empowered through spaces of agency, autonomy and dwelling as they negotiate these spaces and encounter art through technology mediated forms of wayfinding, interpretation and personal curation. Through negotiated agencies of human and non-human, visitors become emancipated, active agents in a process of co-production. Such positioning is further critiqued as the paper investigates the opportunities afforded by augmented reality to create alternative spaces of connection and interpretation through conceptualisations of dwelling and we suggest technology holds the potential to facilitate an enriched, deeper and more personal connection to that experienced in art gallery and exhibition spaces
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