Preparation and thermal decomposition of zinc/copper trimellitates and pyromellitates

The aim of this research was to prepare and characterise zinc, copper and mixed zinc/copper trimellitates (1,2,4-benzene tricarboxylates) and pyromellitates (1,2,4,5- benzene tetracarboxylates). The characterisation included a study of the thermal decomposition for selected salts. The literature is reviewed, discussing the synthesis, structural properties, and thermal decompostions of carboxylate salts. This review highlights the growing interest in benzene carboxylates, and a summary of the applications of such salts is given at the end of the review. The preparative route investigated in the work reported here involved reacting zinc/copper hydroxycarbonate, (Zn(_x)Cu(_1-x))(_n)(CO(_2))(_p)(OH)q, with the carboxylic acid. This preparation was chosen in an attempt to overcome problems encountered during previous projects, which are discussed in the introduction. The preparation and characterisation of zinc/copper hydroxycarbonates were studied, concentrating on the preparation of single phase products. The hydroxycarbonate route was successful in producing single metal and mbced metal salts of trimellitic and pyromellitic acid. Limits of the solid solution series were deduced for the mixed metal carboxylates. Three trimelitate crystal structures, Zn(_2)OH(C(_6)H(_3)(COO)(_3)) . 2H(_2)O, ZnCuOH(C(_6)H(_3)(COO)(_3)) . 2H(_2)O, CuH(C(_6)H(_3)(COO)(_3)) . 2.5H(_2)O, and one pyromellitate structure, ZnH(_2)(C(_6)H(_2)(COO)(_4)) . 6H(_2)O, were determined. The trimellitate structures were all polymeric layers, with the anion bridging between the metal sites. The pyromellitate had an ionic structure with [Zn(H(_2)O)(_6)](^2+) cations and [H(_2)(C(_6)H(_2)(COO)(_4))](^2)- anions. The dianion had very strong, intramolecular H-bonding. Using these and other crystal structures, it was possible to deduce a correlation between IR absorptions for carboxylate groups and the type of carboxylate coordination. The thermal decomposition of the metal salts was studied. An investigation was undertaken using DSC and temperature programmed decomposition to deduce the mechanism for the thermal decomposition of selected salts. The effect of the cation ratio (for the mixed metal salts) upon the decomposition was also studied. The work reported here has shown the success of the hydroxycarbonate route for the formation of polycarboxylate salts. Characterisation for a number of new zinc/copper salts is reported. A study of the thermal decompositions for selected salts has deduced the mechanism and factors affecting the decomposition

Optimum community energy storage for renewable energy and demand load management

While the management of PV generation is the prime application of residential batteries, they can deliver additional services in order to help systems to become cost-competitive. They can level-out the demand and potentially reduce the cost and emissions of the energy system by reducing demand peaks. In this study, community energy storage (CES) is optimised to perform both PV energy time-shift and demand load shifting (using retail tariffs with varying prices blocks) simultaneously. The optimisation method obtains the techno-economic benefits of CES systems as a function of the size of the community ranging from a single home to a 100-home community in two different scenarios for the United Kingdom: the year 2020 and a hypothetical zero emissions target. It is demonstrated that the levelised cost and levelised value of CES systems reach intermediate values to those achieved when both applications are performed independently. For the optimal performance of a battery system being charged from both local PV plants and the grid, our results suggest that the battery should be sized suitable to ensure it can fully discharge during the peak period

Modelling a kinetic deviation of the magnesium hydrogenation reaction at conditions close to equilibrium

A model has been derived for the magnesium hydrogenation reaction at conditions close to equilibrium. The reaction mechanism involves an adsorption element, where the model is an extension of the Langmuir adsorption model. The concept of site availability (σs) is introduced, whereby it has the capability to reduce the reaction rate. To improve representation of σs, an adaptable semi-empirical equation has been developed. Supplement to the surface reaction, a rate equation has been derived considering resistance effects. It was found that close to equilibrium, surface resistance dominated the reaction

Evolution of catalyst coated atomised magnesium spheres: an alternative thermal storage medium for concentrated solar power applications

Elevated temperature cycling studies were performed on two commercial gas atomised Mg spherical powders (average diameter of 26 μm and 30 μm) with magnetron sputtered catalysts (chromium, iron, vanadium and stainless steel) applied to their surfaces. At 350 °C, the presence of a catalyst promotes faster reaction kinetics with improving capacity until approaching stabilisation by the 90th cycle, e.g. the normalised capacity of V_Mg30 was found to rise from 45.5% to 65.5%. Following determination of activation energies (from Kissinger plots) and microstructural analysis of the post cycled structures a mechanism was proposed for the differing evolutions of the uncoated and coated Mg powders based upon a complex process in which particle sintering competes with particle fragmentation. Catalyst effectiveness varied with temperature, having a negligible impact on hydrogen storage characteristics of the atomised Mg powders following 50 cycles at 400 °C and this was mainly associated with the lack of multivalency in the catalysts

An Information Model For Exchanging Hydrological Rating Tables

Many hydrological data systems provide Internet access to observational and processed data in various forms, from websites to web services. This data is generally described with basic metadata, such as units, names of measured variables, spatial coordinates, and so on. This metadata is largely suitable for further analysis or ingestion into hydrological models. However, when the data has been processed through many – potentially complex – steps, more information is required to give users details of implicit assumptions, inaccuracies, or uncertainties that may have been introduced. A common example of this within hydrology is the use of ratings tables to derive variables such as river discharge. Rating tables are generally developed through field observations using a wide range of methods and are subject to constant revision to adapt to changes in the physical world. Extracting details of rating conversions used in any of the hydrological data repositories found on the Internet is currently either not possible or quite difficult. A contributing factor to this is the lack of standard representations for rating tables and their related concepts. This paper describes work by members of the joint World Meteorology Organisation/Open Geospatial Consortium’s Hydrology Domain Working Group on development of an internationally harmonized information model to describe rating tables, called WaterML2.0 part 2. The paper covers the core aspects of the information model, its implementation within web services, and a visualization client for web-based analysis of rating tables. An international data exchange experiment has been setup to further test the information model in a number of exchange scenarios. The results will be used to refine and progress WaterML2.0 part 2 towards an open standard for data exchange. The standard will lead to increased transparency for data derived using ratings, resulting in improved integration with models and other analytical processes

Disordered macrophage cytokine secretion underlies impaired acute inflammation and bacterial clearance in Crohn's disease

The cause of Crohn's disease (CD) remains poorly understood. Counterintuitively, these patients possess an impaired acute inflammatory response, which could result in delayed clearance of bacteria penetrating the lining of the bowel and predispose to granuloma formation and chronicity. We tested this hypothesis in human subjects by monitoring responses to killed Escherichia coli injected subcutaneously into the forearm. Accumulation of 111In-labeled neutrophils at these sites and clearance of 32P-labeled bacteria from them were markedly impaired in CD. Locally increased blood flow and bacterial clearance were dependent on the numbers of bacteria injected. Secretion of proinflammatory cytokines by CD macrophages was grossly impaired in response to E. coli or specific Toll-like receptor agonists. Despite normal levels and stability of cytokine messenger RNA, intracellular levels of tumor necrosis factor (TNF) were abnormally low in CD macrophages. Coupled with reduced secretion, these findings indicate accelerated intracellular breakdown. Differential transcription profiles identified disease-specific genes, notably including those encoding proteins involved in vesicle trafficking. Intracellular destruction of TNF was decreased by inhibitors of lysosomal function. Together, our findings suggest that in CD macrophages, an abnormal proportion of cytokines are routed to lysosomes and degraded rather than being released through the normal secretory pathway

Efficient hydrogen storage in up-scale metal hydride tanks as possible metal hydride compression agents equipped with aluminium extended surfaces

In the current work, a three-dimensional computational study regarding coupled heat and mass transfer during both the hydrogenation and dehydrogenation process in upscale cylindrical metal hydride reactors is presented, analysed and optimized. Three different heat management scenarios were examined at the degree to which they provide improved system performance. The three scenarios were: 1) plain embedded cooling/heating tubes, 2) transverse finned tubes and 3) longitudinal finned tubes. A detailed optimization study was presented leading to the selection of the optimized geometries. In addition, two different types of hydrides, LaNi5 and an AB2-type intermetallic were studied as possible candidate materials for using as the first stage alloys in a two-stage metal hydride hydrogen compression system. As extracted from the above results, it is clear that the case of using a vessel equipped with 16 longitudinal finned tubes is the most efficient way to enhance the hydrogenation kinetics when using both LaNi5 and the AB2-alloy as the hydride agents. When using LaNi5 as the operating hydride the case of the vessel equipped with 60 embedded cooling tubes presents the same kinetic behaviour with the case of the vessel equipped with 12 longitudinal finned tubes, so in that way, by using extended surfaces to enhance the heat exchange can reduce the total number of tubes from 60 to 12. For the case of using the AB2-type material as the operating hydride the performance of the extended surfaces is more dominant and effective compared to the case of using the embedded tubes, especially for the case of the longitudinal extended surfaces

Heteroepitaxial growth of ferromagnetic MnSb(0001) films on Ge/Si(111) virtual substrates

Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent

Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors

Background: Limits on the frequency of whole blood donation exist primarily to safeguard donor health. However, there is substantial variation across blood services in the maximum frequency of donations allowed. We compared standard practice in the UK with shorter inter-donation intervals used in other countries. Methods: In this parallel group, pragmatic, randomised trial, we recruited whole blood donors aged 18 years or older from 25 centres across England, UK. By use of a computer-based algorithm, men were randomly assigned (1:1:1) to 12-week (standard) versus 10-week versus 8-week inter-donation intervals, and women were randomly assigned (1:1:1) to 16-week (standard) versus 14-week versus 12-week intervals. Participants were not masked to their allocated intervention group. The primary outcome was the number of donations over 2 years. Secondary outcomes related to safety were quality of life, symptoms potentially related to donation, physical activity, cognitive function, haemoglobin and ferritin concentrations, and deferrals because of low haemoglobin. This trial is registered with ISRCTN, number ISRCTN24760606, and is ongoing but no longer recruiting participants. Findings: 45 263 whole blood donors (22 466 men, 22 797 women) were recruited between June 11, 2012, and June 15, 2014. Data were analysed for 45 042 (99·5%) participants. Men were randomly assigned to the 12-week (n=7452) versus 10-week (n=7449) versus 8-week (n=7456) groups; and women to the 16-week (n=7550) versus 14-week (n=7567) versus 12-week (n=7568) groups. In men, compared with the 12-week group, the mean amount of blood collected per donor over 2 years increased by 1·69 units (95% CI 1·59–1·80; approximately 795 mL) in the 8-week group and by 0·79 units (0·69–0·88; approximately 370 mL) in the 10-week group (p<0·0001 for both). In women, compared with the 16-week group, it increased by 0·84 units (95% CI 0·76–0·91; approximately 395 mL) in the 12-week group and by 0·46 units (0·39–0·53; approximately 215 mL) in the 14-week group (p<0·0001 for both). No significant differences were observed in quality of life, physical activity, or cognitive function across randomised groups. However, more frequent donation resulted in more donation-related symptoms (eg, tiredness, breathlessness, feeling faint, dizziness, and restless legs, especially among men [for all listed symptoms]), lower mean haemoglobin and ferritin concentrations, and more deferrals for low haemoglobin (p<0·0001 for each) than those observed in the standard frequency groups. Interpretation: Over 2 years, more frequent donation than is standard practice in the UK collected substantially more blood without having a major effect on donors' quality of life, physical activity, or cognitive function, but resulted in more donation-related symptoms, deferrals, and iron deficiency. Funding: NHS Blood and Transplant, National Institute for Health Research, UK Medical Research Council, and British Heart Foundation