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[en] Highlights: •A novel high temperature solar thermal energy storage system is presented. •The system employs a molten metal oxide for energy storage. •The system can achieve a high energy density of 5 GJ/m3. •Oxygen can be also produced as a valuable by-product. -- Abstract: A novel cycle, the chemical looping of molten copper oxide, is proposed with the thermodynamic potential to achieve sensible, latent and thermochemical heat storage with an energy density of approximately 5.0 GJ/m3, which is approximately 6 times more than the 0.83 GJ/m3 of molten salt. This cycle avoids the technical challenges associated with the application of solid materials (especially multivalent metals) for thermochemical energy storage such as attrition, agglomeration, particle breakage and structural change in successive reduction and oxidation reactions, although it brings alternative challenges associated with the handling of molten metal oxides. A process path for the concept is proposed based on data from the literature for the equilibrium composition of copper and oxygen at different temperatures and gas phase pressures. The process has been modelled with codes developed in MATLAB. The calculations estimate that from the total input concentrated solar thermal energy into the system, about 73% can be absorbed, while the rest is lost through re-radiation heat loss. Furthermore, it is estimated that of the absorbed heat, approximately 95% is stored, while the rest leaves the system as high temperature gas. The calculations also predict that approximately 20% of the inlet solar thermal energy is partitioned as the chemical storage, which is also employed for oxygen production. Also reported is the sensitivity to the effects of key operating parameters.
[en] The corrosion behaviour of un-oxidized Fe-Cr binary alloys, in atmospheres typical of the advanced gas-cooled reactor (A.G.R.) can be greatly improved by a vapour-deposited silica coat. Such a treatment would be nearly always applied to steels already partly corroded. The coatings could be damaged during reactor operation. The behaviour of samples simulating these more realistic conditions has been investigated. Silica coatings have been deposited on clean Fe-8.6 Cr binary alloy, and then scratched to simulate damage. They have been deposited on binary alloy which was already extensively corroded, and on a 9% Cr steel typical of that used in A.G.R. power station boilers. The time taken for the samples to reach their linear 'breakaway' oxidation rate was increased by a factor of ca. 10 in all cases. In the case of the damaged sample, the improvement was due to geometrical factors. Analysis of its behaviour has given some insight into the mechanism of breakaway corrosion. If the corroded samples were already in the breakaway condition, silica coatings did not alter their oxidation rate. To be effective the coatings has to be applied before breakaway oxidation commenced. (author)
[en] The investigation of palliative measures, which could increase the corrosion resitance of 9Cr/1Mo steel in the Advanced Gas Cooled Reactor, has been carried out. Methods designed to increase the surface concentration of silicon, boron and chromium were investigated. Silicon and chromium rich surface layers were very effective in reducing corrosion rates; however the design and construction of the AGR boilers make the silicon-based coatings difficult to apply in practice. A method of selective pre-oxidation of the steels to form a chromium rich tarnish layer is the most promising treatment which could be applied to assembled boiler units. (author)
[en] N-(1-Naphthyl)-N'-(3-[125I]-iodophenyl)-N'-methylguanidine ([125I]-CNS 1261) was synthesized as a potential radioligand to image N-methyl-D-aspartate (NMDA) receptor activation. [125I]-CNS 1261 was prepared by radioiodination of N-(1-naphthyl)-N'-(3-tributylstannylphenyl)-N'-methylguanidine using Na125I and peracetic acid. [125I]-CNS 1261 uptake in vivo reflected NMDA receptor distribution in normal rat brain, whereas in ischemic rat brain, uptake was markedly increased in areas of NMDA receptor activation. Radiolabeled CNS 1261 appears to be a good candidate for further development as a single photon emission computed tomography tracer in the investigation of NMDA receptor activation in cerebral ischemia
[en] Cu(I)-catalyzed cycloaddition between azide and acetylene, followed by hydrolysis of ester were performed on micro-patterned self-assembled monolayer to produce smaller features. The reactions were initially performed on mixed monolayers and analysed by water contact angle (CA) and confirmed by X-ray Photoelectron Spectroscopy (XPS). The contact angle measurement has shown a drastic wetting of water on the surface of mixed monolayer indicating that the terminal groups on mixed monolayer has changed into carboxylic acid and hydroxyl terminals. The reactions work in a similar way on micro-patterned SAM and analyzed by using friction force microscope. The emerging of the new lines with high friction force on the border suggested a successful intramonolayer reactions on the border of the patterned SAM.
[en] Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850"∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs
[en] Palladium (Pd) is considered as a possible candidate as catalyst for proton exchange membrane fuel cells (PEMFCs) due to its high activity and affordable price compared to platinum (Pt). However, the stability of Pd is known to be limited, yet still not fully understood. In this work, Pd dissolution is studied in acidic media using an online inductively coupled plasma mass spectrometry (ICP-MS) in combination with an electrochemical scanning flow cell (SFC). Crucial parameters influencing dissolution like potential scan rate, upper potential limit (UPL) and electrolyte composition are studied on a bulk polycrystalline Pd (poly-Pd). Furthermore, a comparison with a supported high-surface area catalyst is carried out for its potential use in industrial applications. For this aim, a carbon supported Pd nanocatalyst (Pd/C) is synthesized and its performance is compared with that of bulk poly-Pd. Our results evidence that the transient dissolution is promoted by three main contributions (one anodic and two cathodic). At potentials below 1.5 VRHE the anodic dissolution is the dominating mechanism, whereas at higher potentials the cathodic mechanisms prevail. On the basis of the obtained results, a model is thereafter proposed to explain the transient Pd dissolution.
[en] The revised (four-step) BCR sequential extraction procedure has been applied to fractionate the chromium, copper, iron, manganese, nickel, lead and zinc contents in urban soil samples from public-access areas in five European cities. A preliminary inter-laboratory comparison was conducted and showed that data obtained by different laboratories participating in the study were sufficiently harmonious for comparisons to be made between cities and land types (e.g. parks, roadside, riverbanks, etc.). Analyte recoveries by sequential extraction, with respect to direct aqua regia digestion, were generally acceptable (100 ± 15%). Iron, nickel and, at most sites, chromium were found mainly in association with the residual phase of the soil matrix. Copper was present in the reducible, oxidisable and residual fractions, whilst zinc was found in all four sequential extracts. Manganese was strongly associated with reducible material as, in some cities, was lead. This is of concern because high lead concentrations were present in some soils (>500 mg kg-1) and the potential exists for remobilisation under reducing conditions. As would be expected, extractable metal contents were generally highest in older, more heavily industrialised cities. Copper, lead and zinc showed marked (and often correlated) variations in concentrations between sites within the same city whereas manganese and, especially, iron, did not. No overall relationships were, however, found between analyte concentrations and land use, nor between analyte partitioning and land use